Esanu Laura Cris tina [619430]

Esanu Laura Cris tina

SOLAR THERMAL SYSTEM USED AT A
SPORTS FACILITY

BACHELOR'S DEGREE THESIS

Study program :
Industrial Design

Brașov
2017 UNIVERSITY OF TRANSILVANIA BRAȘOV
Faculty of Design, Product and Environment
Department of Product design, Mechatronics and
Environment

INTRODUCTION AND AIMS

Renewable energy comes from natural resources which are constantly renewed in relatively short
intervals of time. Currently functioning world economy is based mostly on the use of the energy
from non-renewable resources (coal, oil, natural gas). Factors such as emissions of greenhouse
gases that promotes global warming, pollution, a cidic rains, all due to the use of these
conventional resources, and also alarm signals that attract attention to the fact that oil – the main
sourc e of transport fuels – is depleting, have triggered a process of globally significant
investments to emphasi ze the renewable energy resources.
Solar energy i s the most abundant of all energy resources. When it comes to solar energy, there
are two basic choices. The first is direct energy conversion from solar radiation to electricity,
which is the use of photovo ltaics cells. The second is solar thermal, in which the solar radiation
is used to provide heat to a thermodynamic system, thus creating mechanical energy that can be
converted to electricity.
Today’s solar thermal technologies are efficient and highly rel iable, providing solar energy for a
wide range of applications – from domestic hot water and space heating in residential and
commercial buildings, to swimming pool heating, solar assisted cooling, solar assisted direct
heating, industrial process heat and desalinization.
The thesis proposes the study of solar thermal systems that can be used at a sports facility.

http://isb.pub.ro/docs/Energii_regenerabile.pdf

Part 1

Chapter 1
Sports facility introduction

1.1 Definition of a sport facility

Through “sport s facility” we understand any construction or special arrangement, permanent
or temporary, together with the ancillary rooms required and provided with the adequate
workout and sport s equipment.

1.2 Classification of sports facilities

Classification is essential to the understanding of the structure of the object and its validity
relation to the urban planning and architectural design.
By the nature of their construction that is limited by the operating possibilities in relation
with the different seasons we can distinguish two large groups:
• Outdoor facilities: stadiums , sports fields ;
• Indoor facilities: gyms, indoor swimming pools, artificial rink etc.
In case of outdoor spor t facilities, the activities may be dependent of season and weather .
They can be: stadiums, ski slopes or sports fields. Indoor sports facilities allow the practice of
sports throughout the year in all weather conditions . From this category, there are: basketball
court, volleyball court, handball court, tennis court etc.

a) Outdoor facility [1]
a) Indoor Facility [2]

b) Outdoor basketball court [3] b) Indoor basketball court [4]
c) Outdoor football field [5] c) Indoor football field [4]

d) Outdoor track field [6] d) Indoor track field [4]
Fig. 1 Outdoor facilities : a) b) c) d) Fig. 2 Indoor facilities a) b) c) d)

Also, according to the activity held, sports facilities can also be classified into:
• Simple sport grounds : the practice of one sport;
• Complex sports centre : for practicing various sport ing activities.

1.3 Size

Many people look at the size of the structure, and may regard a facility as small, medium or
large according to the size of the space it occupies. But, this is also influenced by the
capacity of the facility, especially the number of spectators it can accommodate. The size or
capacity of a facility is closely related to the usage it is put to.

1.4 Choosing the construction land

When choosing the land to build a sport e difice it must first be taken into account the
nature and configuration of the soil.
It is recommended that the soil has a high degree of porosity. This ensures good a ir
permeability and oxygen penetration in the soil, which helps soil mineralization and self –
purification. A wet soil (marshes) , with low porosity is polluted and unhealthy , and can
contain hundreds of millions of microbes, including those patho gens (B. tetanus B.
anthraxes ). [7] Since athletes have frequent and hard contact with the ground, they can be
in danger of contact ing these diseases. When choosing instead the construction site for
open type sports facilities, it is necessary to be carried out a chemical -bacteriological
analysis of the soil.
The land should be sunny, dry, and have a sufficient slope to assure a good storm water
drainage to avoid standing rain water , and the first layer of water should be at least 2m
depth. Areas used in the past as dumps, cemeteries are to be avoided. [7]
It is recommended that the sport facility be placed near a flowing water source such that it
can be used to sprinkle the fields, cleaning or in case of fire. Water for drinking, hygiene
use or swimming pools will be used rom the local potable water outlet .
Once the land is chosen further aspect s must be followed [ 8]:
• Stadiums: the playing surface must be smooth, lawn, with as few bumps and
foreign bodies on it and with a security area that surrounds the playing surface of
at least 1 met er from the side -lines .
• Athletics tracks : less and less on clay, modern tracks are covered with synthetic
material that provides better flexibility and easier maintenance . They must be
provided with delimiting borders that do not exceed the track level.
• Jumping pits: filled with fine sand , without foreign bodies, or elastic synthetic
material to ease as good as possible the movement.

If the sports complex will be built in a residential area, it is important to determine to what
extent it corresponds to the existing buildings: according to the number of floors,
architectural appearance, degree of sanitation, the placement, orientation to the cardinal
points, the predominant direction and winds character, presen ce of green areas. The distance
between the apar tment s and public buildings is determined based on insolation and lighting
calculations in line with the standards set out in NRC 2.07.01 -89 "Urban. Systematization
and construction of urban and rural settlements ". [7]

1.5 Orientation of the sport fields

The time of day (early morning or late afternoon) as well as the time of year (winter or
summer) has a bearing on optimum orientation.
The orientation will be done based on the nature of the construction meaning if it’s an
indoor or outdoor playing area. If the playing ground is indoor it will be oriented such that
it will have natural light as much time as possible and if its outdoor such that the light
does not disturb in any way the activities carried on the grounds. It is generally
recommended that play ing areas are orientated approximately in a north -south direction to
minimize the effect of a setting sun on players. The best common orientation is 15° east of
north. [9][10]
However, with more sports being played under lights, this may be less of a concer n.
Limits of good orientation where a uniform direction for all facilities can be arranged [10]:
• athletics, basketball, bowls, croquet, handball, lacrosse, netball, tennis ─ between 20°
west of north and 35° east of north
• football: soccer, five -a-side, Aus tralian rules, Gaelic, rugby league, rugby union ─
between 20° west of north and 45° east of north
• hockey, polo, polocrosse ─ between 45° west of north and 45° east of north
• baseball, cricket, softball ─ between 45° west of north and 35° east of north
Prevailing winds also have to be taken into account. In athletics, the potential problems
caused by strong winds are worse than the inconvenience caused by the setting sun.
Athletes approaching the finish line should not have to contend with strong winds. Pole
vaulters should not be exposed to crosswinds or strong opposing headwinds. The discus is
best thrown into a headwind.
In outdoor diving pools, springboards and platforms should face south.
In shooting sports and archery, outdoor ranges should be const ructed so that the sun is
behind the shooter as much as possible. [11]
Lawn bowling greens must be located away from tall buildings and trees that may cast
shadows over the bowling surface, thereby affecting turf performance. This is not relevant
for synth etic surfaces. [11]

Cricket pitches must run approximately north/south to minimize the risk of batsmen or
bowlers facing a low sun. The pitch axis must point in a direction between 55° and 325°
on the compass. [10]
Tennis courts must be oriented with play along an approximate north/south axis.

1.6 Microclimate

Heating, ventilation and air conditioning are a vital component to achieve comfortable
conditions for the building users. In the case of a sports facilities, the aim should be
conditions to enhance user performance. It is recommended a temperature of 15.5 -20 degrees
Celsius for court sports but a temperature of 15.5 -18.3 degrees Celsius for squash sport s. In
each case, it is recommended a relative humidity of 60% or less and 8 -12 air exchanges per
hour for enclosed courts. For different type of activates American College of Sports medicine
recommends a temperature between 20 to 22 degrees Celsius in the fitness floor area. [ 9]

Chapter 2

SOLAR THERMAL SYSTEMS

2.1 Thermal energy. Definition and energy sources

Thermal energy is the total kinetic energy that a system possesses. Thermal energy is an
important component of the internal energy of such system . [12] Heat is the flow of thermal
energy and can be defined as energy in transit due to differences in temperature between two
systems. [12]
Thermal and electric energy can be obtained through different types of energy sources. They
can be divided in two categories:
• Renewable energy sources : are energy supplies that can be renewed, or replenished
by natural processes in a reasonable amount of time (in years or a human -life span),
once it has been used. Renewable energy is generated from natural sources and
include solar energy, the surrounding temperature, the kinetic energy from water or
wind -power, the energy content of bio -mass, the energy content from ocean waves
and tides, the temperatures of ocean water levels and the energy of the Earth magma
and can be generated again and again when needed. [13]
• Non-renewable energy sources : are energy supplies that are generated from sources
that are available on the earth in limited quantity that will run out or will not
be replenished in our lifetimes —or even in many, many lifetimes. Non -renewable
sources exist in the form o f fossil fuels, natural gas, oil and coal. [14]
Because traditional non -renewable sources are running out fast the attention o f the world is
focused on renewable energy sources and ways to increase energy efficiency. The ideal
scenario is a future were pe ople use cheap and environmental friendly energy sources.
2.2 Solar thermal energy
2.2.1 Solar energy
The sun is probably the most important source of renewable energy available today. [15] It
radiates energy uniformly in all directions in the form of electromagnetic waves. When absorbed
by a body, it increases its temperature. It provides the energy needed to sustain life in our solar
system. It is a clean inexhaustible, abundantly and univ ersally available renewable energy. [16]
The potential of solar energy is enormous: at any moment, the sun emits about 3.86 x 1026 watts
of energy. Most of that energy goes off into space, but about 1.74 x 1017 watts strikes the earth. If
there are no clo uds in the way, then one square meter of the earth will receive about one kilowatt .
Even if only 0.1% of this energy could be converted at an efficiency of only 10% it would be

four times the world’s total generating capacity of about 3 000 GW. Looking at it another way,
the total annual solar radiation falling on the earth is more than 7 500 times the world’s total
annual primary energy consumption of 450 EJ . [17] This validates the fact that the sun is the
most plentiful source of energy on the entire glo be and that it could one day be the most reliant
source of energy.

Fig 2.1 Annual solar energy on the earth [18]

Solar energy can be converted into:
• thermal energy – through solar thermal technology , where heat from the sun is used to
heating up water or air or to make steam.
• electricity – through photovoltaic cells , which directly convert s daylight radiation into
electricity.

2.2.2 Solar thermal systems
The solar thermal system collects the thermal energy in solar radiation and uses it at high or low
temperatures. Low -temperature applications include water and room heating for commercial and
residential buildings. High -temperature applications concentrate s the suns heat energy to produce
steam for driving electrical generators. Concentrating solar power technology has the ability to
store thermal energy from the sunlight and deliver electric power during dark or peak -demand
periods. [ 19]
In other words, solar thermal technologies exploit solar energy that can be used for water
heating, space heating, space cooling and power generating as well.
Solar water heating
The most common use for solar thermal technology is for domestic water heating. The
residential demand for heat can at least partially be covered with a solar water heater, which is a
combination of a solar collector array, an energy transfer system and a storage tank . [20]

Fig 2.2 A solar hot water heating system [21]

A solar water heater is a renewable energy technology that heats cold water using the sun’s
energy. The main components of any solar water heating system are one or more collectors to
capture the sun's energy and a well -insulated storage tank. In north hemisphere, solar collector s

are mounted on the south side of a roof where they can capture most sunlight . These collect the
heat from the sun and use s it to heat up water which is stored in a tank. The hot water is piped to
faucets when tap water is used.
The most common domestic types of solar water heaters are evacuated tube collectors , glazed
flat plate collectors and unglazed plastic collectors used mainly to heat swimming pools.

a) b) c)
Fig 2.3 Solar water heaters :
a) Evacuated tube collectors [22] b) Glazed flat plate collector [23] c) Unglazed plastic
collectors [24]

Solar Space Heating
A solar space heating system can either be active, passive or a combination of both. [25]
A passive solar home is designed and positioned in such a way as to take optimal advantage of
the solar energy that reaches the home. For example, large south -facing windows, and materials
with high thermal mass that absorbs warmth during the day and release the warmth at night when
it is needed most.
Homes with active solar e nergy systems for space heating use mechanical equipment such as
collectors combined with pumps, fans, and blowers to help with the transfer and distribution of
heat throughout the house.

Fig 2.4 One type of home solar space heating system [26]
Solar Space Cooling
The heat from a solar collector can also be used to cool a building by using solar absorption or
adsorption coolers. Solar heat is an energy source . Solar absorption /adsorption coolers use a
similar approach with home air conditioner s, combined with some very complex chemistry
tricks, to create c ool air fro m solar energy . [21][27]

Fig 2.5 Scheme of solar operated absorption air conditioner [28]

Solar Thermal Power Plants
The common basic principle of solar thermal power plants is to use the sun’s energy to generate
electricity on an industrial scale. By using giant parabolic mirrors, sunlight is concentrated on an
absorber tube through witch a heat -transfer fluid flows . The fluid is heated at very high
temperatures and it is then circulated through pipes so it can transfer its heat to water to produce
steam . The steam is converted into mechanical energy in a turbine, which powers a generator to
produce electricity . [29]
Fig 1.4 Solaben Solar Power Station facility Spain [30]

2.3 Solar water heating systems
2.3.1 Classification of solar water heating systems
We can classify solar water heating systems by several criteria:
1. By the fluid heated in the collector. When the fluid used in the application is the same
that is heated in the collector it is called a direct or open loop . In opposite , when the fluid
heated in the collector goes to a heat exchanger to heat up the utility fluid, it is called an
indirect or closed loop . [20] A closed loop system uses some kind of a special fluid with
anti-freeze properties that has a much lower freezing point than water, yet readily absorbs
and releases heat. [31]
2. By the circulation system of the fluid we can distinguish:
• Natural systems – no pumps are required;

• Active or forced -circulation systems – electric pumps, valves and controllers move
the water between the collectors and the storage tank
2.3.2 Natural Solar Water Heating Systems
The Natural solar heating system do not use any pumps and relies on natural convection to
circulate the water through the collectors . Though natural solar water heating systems cost
less than active systems they are less efficient and can overheat or freeze.
They can be divided into two basic types [32]:
• Integr al Collecto r Storage
Integral Collector Storage systems , also called a “batch” or “breadbox” water heater,
combine a solar collector and water storage tank into one single unit. [33]
• Thermosiphon
The T hermosiphon system takes advantage of natural convection and gravity. Hot water rises
as cold water sinks because gravity pulls down the relatively heavier cold water molecules.
Since warm water rises and cool water falls in convection, the storage tank should always be
placed above the solar collectors.

a) Schematic diagram b) Photograph
Fig 2.7 Schematic diagram and a photograph of a thermos iphon system [34] [ 35]

2.3.3 Active Solar Water Heating Systems
Active systems use electrically driven pumps and valves to force the fluid to circulate from
the collector to the storage tank and the rest of the circuit.
There are three types of active solar water heating systems [ 36]:
➢ Direct circulation systems
➢ Antifreeze indirect -circulation systems
➢ Drainback indirect -circulation systems
The drainback system use pumps to transport water through the collectors. When the system is
not in use , the pump switches off and the water drains from the collectors by gravity into the
drainback vessel , eliminating the risk of freezing in cold climates.

Fig 2.8 Schematic diagram of a direct circulation system [37]

Fig 2.9 Schematic diagram of an indirect water heating system [37]

Fig 2.10 Simple Drainback system [38]

Chapter 3
Identification and description of the main components of a thermal
solar system
The solar collector is the most expensive and most critical component of a solar thermal system.
Besides the collector, a solar thermal system also consi sts of other system com ponents. Essential
are a liquid or gaseous heat transfer medium and pipes to transport the heat transfer medium.
Normally, a heat store with none, one or several heat exchangers plus, for certain designs, pumps
with a drive to maintain the heat carrier cyc le, sensors and control instruments are required. [39]
3.1 Solar collectors
3.1.1 Definition
Solar power has low density per unit area (1 kW/ m2 to 0.1 kW/ m2). Hence, it is to be collected
by covering large ground area by solar thermal collectors. Solar thermal collectors essentially
form the first unit in a solar thermal system. It absorbs solar energy, converts it into heat and then
transfers it heat transpo rt fluid. The heat transport fluid delivers this heat to thermal storage
tank/boiler/heat exchanger, etc. to be utilized in the subsequent stages of the system. [16]
3.1.2 Classification
Solar collectors can be classified into [ 40]:
• stationary (or non -concentrating) ;
• concentrating systems.
The main difference between them is the way they collect solar radiation. The stationary
collectors absorb beam as well as diffused radiation as it is received on the collector , while for
concentrating -type solar collector s solar radiation is converged from a large area using optical
means and they mainly make use of the beam radiation component (plus very little diffuse
component coming directly over the absorber).
A classification of various solar collectors is done in Fig. 3.1.

Fig 3.1 Classification of various solar collectors

3.1.3 Flat-plate collector s
Flat-plate collectors can be designed for applications requiring energy delivery at moderate
temperatures . They use both beam and diffuse solar radiation, do not require tracking of the sun,
and require little maintenance. They are mechanically simpler than concentrating collectors and
have a long lifetime . The major applications of these units are in solar water heating, building
heating, air conditioning, and industrial process heat.
The typical flat -plate collector has the following main components [ 41] [ 42]:
➢ Glazing cover which may be one or more sheets of glass or a radiation -transmitting
plastic film or sheet that transmits radiation to the absorber, but prevents radiative and
convective heat loss from the surface .
➢ Tubes, fins, passages or channels which carry the water, air or other fluid from the inlet
to the outlet.
➢ The absorber plate with tubes, fins or passages attached to it. The plate is usually
metallic (copper, aluminium , steel or ceramic ) and painted flat black or electroplated with
a selective absorber, although a wide variety of other materials can be used, particularly
with air heaters.
➢ Insulation covering sides and back of the collector to reduce the heat losses.
➢ Container or casing to enclose the other components and protect them from dust and
moisture.

Fig 3.2 Typical flat -plate collector [42]

The transparent cover and the insulation may be omitted for low temperature rise applications,
such as heating for swimming pools.
3.1.3.1 Glazing materials
The purpose of glazing or transparent cover is to transmit the shorter wavelength solar radiation
but block the longer wavelength radiation, from the absorber plate, and to reduce the heat loss by
convection from the top of the absorber plate.
Glass is the most common used material to glaze solar collectors [ 43]. Glass material has highly
desirable property of transmitting as much as 90% of the incoming short -wave radiation, while
virtually none of the long wave radiation emitted by the absorber plate can escape outwards by
transmission . [44] Glass with low iron content has a relatively high transmittance for solar
radiation (0.85 -0.90 at normal incidence) [45] [ 46] Transparent plas tics, such as polycarbonates
and acrylics are also used as glazing for flat plate collectors, but because most usable varieties
also have transmission bands in the middle of the thermal radiation spectrum, their longwave
transm ittance can be as high as 0.4 0.[45][47]
To minimize the upward heat loss from the collector, more than one transparent glazing can be
used. However, with the increase of the number of the cover plates, transmittance is decreased.

Fig 3.3 Spectral transmittance of 3mm Low Iron Float Glass [47]

Fig 3.4 Transmittance of multiple glass coverings having a index of refraction of 1.526 [47]

3.1.3.2 Absorbers
The purpose of the absorber is to absorb as much of the irradiation passing through the glazing as
possible, reemit as little as possible, and allow efficient transfer of heat to a working fluid. The
absorber plate material should have high thermal conductivity, adequate tensile and compressive
strength, and good corrosion resistance [ 48]. Copper is generally preferred because of its high
thermal conductivity and high corrosion resistance . Other suitable materials used for absorber
plates include copper, aluminium , stainless steel, galvanized steel, plastics, and rubbers. [47]
Fig 3.5 Absorber -plate design [47]

In order to increase the absorption of solar radiation and to reduce the emission from the
absorber, the metallic absorber surfaces are painted or coated with flat black paint or some
selective coating. A selective coating has high absorptivity in the solar wavelength range (0.3 to
3.0 μm) . [47]
3.1.4 Evacuated -Tube Collectors
Another type of solar collector used in solar thermal systems consists of rows of glass tubes
connected to a common header at the top. Inside each tube is a vacuum (hence the name
evacuated tubes) that acts as an insulator reducing convection and conduction heat loss therefore
making the collector more efficient than flat -plate collectors, especially in colder climates with
low level diffuse sunlight. [49]

Fig 3.6 Heat Pipes [50]

There are two types of evacuated tube collectors [ 51]:
• Direct flow – the heat transfer fluid is circulated through copper tub es attached to a
absorber plate mounted inside the evacuated tube.
• Heat pipes – uses a heat pipe attached to the absorber plate. The heat pipe transfers the
heating energy to the condensing section of the heat pipe where the collector fluid is
warmed. This takes place in the header where the evacuated tubes are connected.
The most co mmon evacuated tube is a direct flow collector consisting of two glass tubes fused
together. Within the vacuum is located between the inner and outer glass. The solar absorbing
coating is sputtered onto the outside of the inner glass tube. A heat conductor/transfer sheet is
located inside the inner glass tube that conducts the heat to the manifolds . [52] The vacuum tube
collector can be paired up with a parabolic reflector located behind each tube to enhance
performance . The solar radiation that pa sses through each tube will be reflected to the underside
of the cylindrical absorber in the collector tubes . [49]
3.1.5 Concentrating Collectors
These collectors use mirrors or Fresnel lenses to concentrate sunlight onto a small area to
produce high temperatures . Such high temperatures are needed for industrial uses and for
making steam in electrical power generation. Because they use only direct -beam sunlight,
parabolic -trough systems require tracking systems in order to obtain the optimal benefit.
These collector systems require large areas for installation, so they are usuall y ground
mounted. [51]

a) Parabolic Through [53] b) Dish [54]

b) Central receiver [55]
Fig 3.7 Main types of concentrator collectors

3.2 Storage tank
Beside the collectors, the storage tank is the second essential component of solar thermal
systems, since solar energy is a time -dependent energy resource. The solar tank stores the solar –
heated water until it is needed. [56]
The main types of cylinders fo r domestic water production are:
a) Simple tank (Fig 3.8 a)
b) Single Coil Cylinder (Fig 3.8 b)
c) Twin Coil Cylinder (Fig 3.8 c)

a) b) c)
Fig 3.8 Storage tank/boiler []

Storage tanks can be classified according to various criteria [58]:
• Application
• Positioning: Vertical or horizontal type
• Stratification device: with or without
• Material: stainless steel , vitrified steel , copper or others
• Internally or externally heat exchanger
3.3 Pump station
Solar pump stations are used on the solar loop of a solar thermal system to circulate the heat
transfer fluid through the array. They are also used to control the temperature in the solar storage
tank.
The main components of a pump station are:
• Circulating pump – in solar thermal systems with forced circulation a pump is required
to move the heat transfer f luid through the piping circuit [59];

• Thermometer – in solar thermal systems for hot water production, they are meant to
indicate the flow and return temperat ures from the solar circuit [60];
• Pressure gauge – provides a visual indication of system pressure [59];
• Volumetric flowmeter – helps in measuring the heat -transfer fluid’s flow rate [59];
• Over pressure' safety relief valve – ensures that the system pressure limit isn’t
exceeded , and protects the piping and components from extreme overheating or loss of
circulation [59].
• Valves – devices with adjust ment and control functions in the circuit [61].

Fig 3.8 Pump station [62]

3.4 Solar controller
justifies running the pump to tran sport to the solar storage. To do
this, the controller compares the collecto r temperature using the
collector sensor and the temperature in the lower area of the storage
tank (tank sensor). [63]
3.5 Expansion Tank
The expansion tank is a safety device that prevents pressure
increases due to thermal expansion of the solar fluid, ensuring that
the maximum operating pressure is never reached. In closed loop
systems, expansion tanks are critical elements and must be appropriately sized for the system to
operate properly. For expansion tanks, the acceptance volume must be sufficient to accommodate
expansion of the heat transfer fluid when the solar loop goes into stagnation. [65]

Fig 3.10 Expansion tank [66]

The solar controller is an electronic device that decides when there is suffi cient solar energy
available in the collectors that

Fig 3.9 [64]

Part 2

Chapter 4
Case study – Dimensioning of a solar thermal system at a sport
facility
In this chapter, we will dimension a solar thermal system for hot water for a sport facility. The
case study will be conducted on a sports facility located in Brasov, Romania.
4.1 Solar potential in Romania
In the spring se ssion of the European Council of 9 March 2007, the European Union adopted a
new policy on renewable energy and set the objective of in creasing the share of renewable
energy in total energy consumption by up to 20% (later increased by Directive 2009/28 / CE to
24%) until the year 2020 , as part of the so -called 20/20/20, as subsequently amended by
Directive 2009/28 / CE. Hence, a s a member of the European Union, Romania has the obligation
to support and promote renewable energies in order to achieve this objective. [6 7]
Romania has an average of 210 sunny days a year and annual solar flu x ranging from 1,000
kWh/m2 / year to 1,3 00 kWh/m2 / year, placing it among countries with notable solar potential.
Of this, around 600 -800 kWh / m2 / year is 100% useable. [6 8]

Fig 4.1 Global Horizontal Irradiation for Romania [69]

4.2 General presentation of the sport facility
Brasov is located in the central part of the Country. It is surrounded by the Southern Carpathians
and is part of the Transylvania region.
The sport facility chosen for the case study is Tennis Arena Club located on Grivitei 1W Street
in Brasov. Tennis Arena has 9 clay courts : 3 in the main hall, 3 in an inflatable sports dome and
3 outside. Therefore, the sport base has 6 useable tennis courts no matter the weather or the
season.

a) Main hall
b) Outside Courts c) Inflatable sports Dome
Fig 4.3 Tennis Arena Brasov [70]

The main hall has a surface of 2000 m2. The ceiling is made out of wood and the curved roof is
made of metal sheets fastened with screws on wood . Beside the 3 tennis courts t he main hall is

equipped with desk reception, 2 locker rooms and 3 gym rooms for ball et, aerobic and boxing
classes. Each locker room include 3 showers and 2 washrooms.

Fig 4.4 The main Hall interior [70]

4.3 System Design
Preliminary studies are carried out before de signing the water supply system for d omestic hot
water. They are aimed at estimating the potenti al interest of the future installation in relation to
the domestic hot water dem and (quantity and regularity on d uring the year) as well as the
existence of technical o r architectural constraints by:
– dimensioning of the installation taking into ac count the different constraints;
– cost estimation;
– estimation of provisional savings. [71]

4.3.1 Estimating the hot water demand
To estimate the hot water demand, a rough calculation regarding the number of athletes and the
hot water consumption in an average week was carried.
The Tennis Arena schedule is:
• 7-24 from Monday to Friday – 17 working hours
• 9-20 in the Weekend – 11 working hours
To approximate the average number of persons in an hour several factors have been taken into
account: the fact that tennis can be played in two and four persons; good and bad weather days;
full and slow days (when either all the courts are full or all are empty).
We came with a rough average number of 11 peop le per hour.
17×11=187- average number of persons/ day from Monday to Friday
11×11=121- average number of persons /day in the Weekend
(187×5+121×2) /7=168- average number of persons/ day
We assume that from the total number of person s per day 60% of them sho wer at the facility:
168×0.6=1 01 persons
For every shower, an athlete uses 25 litters of hot water at a 60°C [ 72] so the total hot water
demand is:
101×25= 2525 litter s per day
4.3.2 Local solar radiation
By studying the Global Horizontal Irradiation map for Romania, Brasov has a Global Horizontal
Irradiation between 1100 -1300 kWh/m2 having a medium solar potential.
By using “NASA Surface meteorology and Solar Energy” we obtain further meteorological data
related to solar radiation for Brasov.
NASA Surface meteorology and Solar Energy is a renewable energy resource web site that
displays various information (s olar radiation, wind speed, atmospheric pressure, air temperature
and humidity ) for photovoltaic and renewable energy system design needs.
The database includes:
• over 200 satellite -derived meteorology and solar energy parameters
• monthly averaged from 22 years of data
• data tables for a particular location

Fig 4.2 [73]

4.3.3 Site assessment
It is essential to make a site assessment before designing a thermal system to be able to avoid
planning errors. This gives a designer an opportunity to see the basic conditions and limiting
factors of the site.
The site assessment concerning Tennis Arena Building was carried out on the date of May 6th,
2017. Suitability for installation, building orientation, available area for installation, far and near
shading objects and possible mounting options were investigated during this assessment.
The façade of t he main building is oriented to south. There are no near large buildings, trees or
other obstacles that can cause shading on our system installation.
Usually the roof of a building seems the most normal place for installing collectors because of
space optimization. This way unused space can be put to work.

Fig 4.3 Roof of Tennis Arena
Unfortunately, the Tennis Arena roof is not ideal for our installation because:
• The roof is not ideally oriented to south and because of the orientation and height of the
building it will resulting in energy losses;
• A possible reinforcement of the roof will be required to withstand the weight of the
collectors;
• Possible angle restriction because of snow in the winter.
Therefore, the system will be mounted on a nearby ar ea on the ground.

Fig. 4.4 Mounting Area

The mounting location is on the left of the building, near the locker room, so heat losses will be
reduced.
4.3.4 Collector orientation
Optimization of a collector orientation is an important process in order to collect as much
irradiance as possible on the surface of the collector . To be able to this, collector inclination
angle (β) and azimuth angle ( γ) should be optimized.

Fig 4.5 Solar angles [ 74]

The collector field should be directed towards south (γ=0 °) in northern hemisphere in order to
collect maximum available irradiation on the plane.
Optimum inclination angle is determined according to the application of the system . In this
study, the inclinatio n angle is chosen for annual year-round water heating. Optimal tilt angles are
lower for hot water production and swimming pool warming because of the highest height of the
sun during the summer. For hot water, the inclination angle is chosen between 15°-45° [72]
The general rule of thumb to determine the optimal inclination angle is taking latitude equal to
inclination angle. [74] However, from the NASA Surface meteorology and Solar Energy we see
that the annual irradiance is higher in Brasov at a til t of 30° than 45°. T his differentiation results
from the fact that for the locations with larger latitudes, the difference between winter and
summer irradiation increases.
For our study, the orientation will be done at γ=0° and β=30°.
4.3.5 Calculation of the number of collectors and the size of the storage tank
First of all, in designing a solar thermal system the designer must appreciate what kind of
collector is better suited in the installation by taking in account orientation, placement
restrictions, yearly solar radiation and cost.
For domestic hot water, t here are two types: flat -plate and evacuated tube collectors. Both types
of collectors have advantages and disadvantages. For our system, we will use flat -plate collectors
because we are designing only for hot water, they cost less and because the mounting is on the
ground we are not restricted as in a roof mounting.

It is determined that we will need a total of 20 flat plate collectors with an aperture surface of
35m2. The number of collectors is determined for a daily consumption of 2500 l in a region with
solar radiation between 1200 -1400 kWh/m2 (Brasov radiation) by consulting the chart in in Solar
System Design Catalog . [71]
The size of the solar tank is calculated by intersection o f the vertical line (the correct v alue of the
need) with the c orresponding line curve (see fig. 4.5) :
– Curve for high variability in weekly consumption
– Curve for low variability in weekly consumption
More regular weekly consumption profiles can be better " damped " by means of a larger size
solar tank.

Fig 4.5 Solar system design catalog [72]
By consulting the chart , for 2500 l/day of water needed for high variability in weekly
consumption , the storage tank needs to have a capacity of 3000 l.
4.3.6 Hydraulic sizing of the installation
4.3.6.1 Total solar system flow rate
Our system works in a normal “flow”, meaning that the recommended flow rate of the heat
transfer fluid, is between 40 and 60 l / h per m² of the collector area at a flow rate equal to or less
than 1 m / s.

4.3.6.2 Collector Array
Depending on the location and the concept of the installation, the collectors can be connected in
series or in parallel . Series connection guarantee uniform flows but the pressure drop is likely to
be prohibitive, especially in large arrays. Whenever colle ctors are put in series, the pressure drop
should be checked. The parallel arrangement is favourable from a pressure drop point of view,
but it requires more piping and larger pipe dimensions due to larger flow rates. [76]

Fig 4.6 Conections:Parallel (left) and Series (right) [72]
The most manufacturers recommend only 5 to 6 collectors to be connected in t he parallel
arrangement. In the serial arrangement, the maldistribution problems do not occur, but a h igh
number of collectors in the array will, ho wever, entail too high pressure drop. [76] To avoid any
flow difference in the collector fields, it is important that the number of collectors in series / row
is the same.
For our case study with 20 flat -plate collectors , we came with the following arrange ments:

a) Two arrays

b) Five arrays
Fig 4.7 Possible collector array connections Series -parallel

When choosing the collector array, we must think of pressure losses but also in terms of space.
In that manner, we will also take into account the fact that w hen installing seve ral rows of
collectors in series behind each other, suitable clearance to prevent shading must be maintained.
To determine the clearance, we require the angle of the sun at midday on the 21.12, the shortest
day of the year. In Brasov, this angle is 20 .87°. [ 77] [ 78]
The resu lting clearance between rows is calculated as follows [77]:
𝑧
ℎ=sin⁡(180°−(𝛼+𝛽)
𝑠𝑖𝑛𝛽

Fig 4.8 Row clearance [77]

z = Collector row clearance
h = Collector height
α = Collector angle of inclination
β = Angle of the sun
For Brasov with a collector of 2 m height, angled at 30° :
𝑧
2𝑚=sin⁡(180°−(30°+20.87°)
𝑠𝑖𝑛20,87°=2,177
z=2*2,177=4.35 m
The centre dimensi on z of the collector rows must be at least 4.35 m.
By takin g into account the fact that we have to leave between each row a clearance of 4.35 m we
will use the two -array connection because it better fits our space.
A final overall scheme for our water heating system is represented in Fig 4.8.

Fig 4. 9 System scheme

4.3.6.3 Sizing of the collector circulation pump and the pipe diameters
When sizing the pump, the pressure drop calculation must not be carried after choosing the
pipes, but rather simultaneously because, depending on the calculation result there may be
needed modifications in the pipe dimensions.
To choose a proper pump we will require two things: pump head and flow rate . The head
represen ts how high the pump can lift a column of water and the flow by how much fluid
(gallons or litters ) a pump can push at a given head. [79]
The following rough procedure to cover closed loop systems assumes a 50 -50 water glycol
antifreeze mix for a temperature of 60°.
Our system with 20 flat-plate with 35 m2 absorber area, and a required specific flow rate of 40
l/(h · m2) has a throughput of 1400 l/h or 23.3 l/min. [77]
We will multiply the collector flow rates by 1.15 to account for its lower heat transfer capability ,
because antifreeze increases viscosity and pipe friction losses, and also the antifreeze has a lower
heat capacity, so more antifreeze mix must be circulated to transfer the same amount of heat out
of the collector. [80]
Target Flow Rate=23.3* 1.15=26.7l/min
Because there is no static head (the fluid is circulated back to the same level) we will only
calculate the dynamic head. In this step, we will estimate pipe sizes, and then calculate the total
pressure drop through the system for: 1) the collectors, 2) the supply and return pipes and the
fittings in these pipes, and 3) any valves or other pressure drop causing components.

We will calculate friction loss for 10 m of pipes. Because friction loss calculations are
complicated we will use S F Pressure Drop 8.0 a software that calculates pressure d rops of
flowing liquids and gases in pipes (laminar and turbulent flow) [].
By consulting Fig 4 .10 for a flow rate of 25 l/min we will use DN 32 copper pipes. Also, we will
have: 2x Tee, 2x Circular bend and 4x check valve. The flow medium is a mixture of 50% water
and 50% glycol.

Fig 4. 10 Flow Velocity [77]

Fig 4.11 SF Pressure Drop 8.0

Collectors (even those connected in parallel in one array ) contribute significantly to pressure
losses and, therefore, it is extremely important not to be neglected. The collector manufacturer
must provide pressure loss curves with at least two reference flows. [72]
For the sake of our calculation we will use a chart from a flat plate manufacturer. For a flow of
0.068m3/h there is a p ressure loss of 1.8 mbar / solar collector.

Fig 4.12 [77]

Project:
1 2 3 4
1. Flow medium
Flow medium Mixture (1.013 bar, 60 °C) Mixture (1.013 bar, 60 °C) Mixture (1.013 bar, 60 °C) Mixture (1.013 bar, 60 °C)
Condition liquid liquid liquid liquid
Volume flow m3/h 1.44 1.44 1.44 1.44
Mass flow kg/h 1460.1096 1460.1096 1460.1096 1460.1096
Volume flow branch.pipe m3/h
Density kg/m3 1013.965 1013.965 1013.965 1013.965
Dyn.Visvos. 10-6 kg/ms 771.746 771.746 771.746 771.746
Kin.Viscos. 10-6 m2/s 0.761117001 0.761117001 0.761117001 0.761117001
2. Additional data for gases
Pressure (inlet, abs.) bar
Temperature (inlet) °C
Temperature (outlet) °C
Norm volume flow Nm3/h
3. Element of pipe
Pipe identification
Element of pipe circular Circular bend Tee, sharp edged Check valve globe lift
Number 1 1 1 1
Dimensions of element SI ######################### ######################## ######################## #######################
Length of pipe L: 10.0.00 m Radius R: 100.0.00 mm ########################
Angle w: 90.0.00 degree
4. Result of calculation
Veloc.of flow m/s 0.497359197 0.497359197 0.497359197 0.497359197
Reynolds number 20910.70661 20910.70661 20910.70661 20910.70661
Veloc.of flow 2 m/s 0.101859164
Reynolds number 2 6691.426117
Flow turbulent turbulent turbulent turbulent
Absolute roughness mm 0.03 0.03
Pipe friction number 0.027575567 0.027575567
Resistance coefficient 8.617364794 0.512862921 1.012582912 18.03314478
Resistance coefficient branch.pipe
Press. drop branch.pipe mbar
Pressure drop mbar 10.80706475 0.643183029 1.269883468 22.61542454
Pressure drop bar 0.010807065 0.000643183 0.001269883 0.022615425
Sum Pressure drop bar 0.010807065 0.011450248 0.012720131 0.035335556

Fig.4.1 3 Pressure drop results

By adding all the pressure losses, from the pipe, fittings and collectors we obtain 0.205 bar.
0.205 bar = 2.09 meters head
Because we don’t want a pump that just barely have enough head, we can oversize it a bit and
choose a pump with 2.5-3 m pump head with a flow of 26.7 l/m. T o determine which pumps
might meet those criteria pump curves are used.
4.3.6.4 Sizing the expansion vessel
In closed loop systems, the expansion vessel must be appropriately sized for the system to
operate properly. For expansion tanks, the acceptance volume must be sufficient to accommodate
expansion of the heat transfer fluid when the solar loop goes into stagnation. For closed loop
solar systems, the expansion tank must be acceptable for use with propylene glycol or other heat
transfer fluid used in the collector loop.
In our sizing, we used the table below (Fig 4.12) to select the coefficient for a 50% glycol mix at
the temperature of 130°.Further we used an online excel sheet where we introduce our
parameters. The result is that the volume of the expansion vessel is 295 l, so next available to
market would be an expansion vessel of 300 l.

Coefficient n according to temperature
°C -20 -10 010 20 3040 50 60 70 80 90 100 110 120 130
%
0 0 0.1 0.2 0.4 0.8 1.2 1.7 2.3 2.9 3.6 4.3 5.2 6 6.9
10 0.1 0.3 0.5 0.7 1.1 1.5 2 2.6 3.2 3.9 4.6 5.5 6.3 7.3
20 0.2 0.5 0.8 1.1 1.4 1.8 2.3 2.9 3.5 4.2 4.9 5.8 6.7 7.6
30 0.1 0.4 0.7 1 1.3 1.6 2.1 2.6 3.1 3.8 4.4 5.2 6 6.9 7.8
40 0.4 0.7 1 1.3 1.5 1.7 2.1 2.5 3 3.6 4.2 4.9 5.6 6.4 7.3 8.2
50 0.6 0.9 1.2 1.5 1.8 2 2.4 2.8 3.3 3.9 4.5 5.2 5.9 6.7 7.6 8.5glycol

Fig 4.14 Coefficient n [81]

Closed expansion vessel calculation for heating installations
Va= 1400 l The volume of water in the heating system
Vv= 7l The volume of safe water – not less than 3 liters 0,5% din Va
tm= 130°C Maximum water temperature in the heating system
n= 8.5 Coefficient of expansion of water according to the maximum temperature of the installation n= 0.31 + 0.00039· tm²
e= 0.085 Water expansion coefficient n/100
Pst= 3bar Hydrostatic pressure at the point of installation of the expansion vessel
Pvs= 7bar The pressure at which the safety valve is adjusted
P0= 3.3bar Pre-charge pressure of the expansion vessel on the gas side Pst + 0,3 bar
Per= 6.5bar Maximum pressure on the gas side of the expansion vessel Pvs – 0,5 bar (10% Pvs if Pvs > 5 bar)
Pa= 4.3bar The initial absolute pressure on the gas side of the expansion vessel P0+ 1 (where 1 is the atmosferic pressure)
Pe= 7.5bar The maximum absolute pressure on the gas side of the expansion vessel Per+ 1 (where 1 is the atmosferic pressure)
Vn= 295.3125 l The volume of expansion vessel required
The data we are interested in are:
Expansion vessel volume required – Choose the next available value on the market
The preload pressure of the expansion vessel on the gas side will have to be the result of the calculation = P0
The hydrostatic pressure at the point of installation of the expansion vessel is due to the water column
A 10 meter water column presses with a pressure of 1 bar
Fig 4.15 Expansion vessel calculation [ 81]

3.4 Collector mounting
3.4.2 Frame
A frame should stabilize and maintain the solar collector. Therefore, planning the frame is one
very important part of the installation of the solar panel. We will model a frame for two
collectors. The frame can be used modularly to obtain different combinations.

Part 3
Techno -Economic Feasibility Analysis

A Techno -Economic analysis will be conducted to provide us with information regarding cost
and the amortization period and also to prove the practicability of the project.
Chapter 5
This economic analysis is designed according to the technical framework described in Part 2 –
Chapter 4. Many of the required in puts were satisfied using data from Chapter 4 but the actual
equipment considered for use will be chosen in this chapter.
5.1 Input data
Technical project
1.Project theme
Water heating for Tenis Arena sport facility for a number of 100 persons/day
2.Hot water demand
2500 l/day hot water at 60°C→107.5 kWh/day []
3.Availability of solar energy

Fig 5.1 Insolation on a horizontal surface []

4.Solar thermal system
• Closed loop forced circulation system
• 35m2 absorption collector area.
• 20 Flat -plate collectors
• 3000 l storage tank
5.2 Selecting the main system components
5.2.1 Flat -plate collector
Ariston Kairos CF 2.0

➢ Absorber with highly selective treatment to titanium
oxides (95% absorption reflection 5%)
➢ 44 mm toughened hail -proof anti -reflective glass
➢ Hydraulic circuit with copper pipes
➢ Harp geometry and ultrasound welding
➢ Designed and sized in systems with forced
circulat ion
➢ Can be inclined between 30° and 60°
➢ Test report according to EN 12975
➢ Aperture surface m2 – 1,82
➢ Absorbent surface m2 – 1,74
➢ η0 – 0,738

Fig 5.2 Kairos CF 2.0

5.2.2 Storage tank
ELBI – BF1-3000 with extractable Heat exchanger

Fig 5.3 []

5.2.3 Pumping Station
Two-line solar station DN20 TACOSOL ZR -HE

Fig 5.4 []

5.2.4 Controller
STECA 301 PWM controller

Fig 5.5 []
5.2.5 Expansion vessel
VAS DE EXPANSIUNE VAREM, DIN OTEL, CILINDRIC, VERTICAL, 6 BAR, 100L

5.2.6 Auxiliary energy source
The auxiliary energy source works when there is not enough solar radiation to cover the energy
demand for hot water.
Usual solutions:
-heat pump

-electric heater
-gas heater
5.3 Techno -Economic Analysis
5.3.1 Costs
Costs are divided between :
• Initial investment cost
• Operating cost
• Maintenance cost
The initial investment cost consists of the total value of the initial equipment or other
supplementary components needed for the solar thermal system.
Components UM Euro/Um Necessary quantity for a
35m2 absorption area
Collector – Ariston Kairos CF 2.0 buc 311 20
Collector mounting structure for 2
collectors buc 129 5
Storage tank – ELBI – BF1-3000 buc 4046 1
Pump Station – DN20 TACOSOL ZR -HE buc 219 1
Controller – STECA 301 PWM buc 92 1
Expansion vessel (100 l) buc 106 1
Fittings for 1 collector set 15 20
Connectors between collectors set 8 16
Antifreeze fluid l 5 30
Total value of equipment 11906
Installation cost 20% 2381
Total 14287

Regulated rates for household customers who have not exercised their eligibility established by
The National Energy Regulatory A uthority valid from 1 July 2017 a ccording to Order no.
175/2015 (published in MO No 4 81 / 26.06.201 7) []

Tension
level Tariff CS – social type Tariff
CD-
monomia
l type Tariff CR -monomial
with reservation type Tariff CR2 – monomial with
reservation type, differentiated on
two time schedules Tariff CR3 – monomial with reservation type,
differentiated on three time schedules
Part I
(lei/kWh
and
subscriber) Part II
(lei/kWh
and
subscriber) Part III
(lei/kWh
and
subscriber) Energy
price (lei/
kW) Reservation
price (lei/day
) Energy
price (lei/
kW) Reservation
price (lei/k
W) Energy
price in
day
time(lei/
kW) Energy
price in
night
time
(lei/kW) Reservati
on
price (lei/
day) Energy price
in rush
zone (lei/kW) Energ y price
in normal
zone (lei/kW) Energy price
in gap
zone (lei/kW)
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Low
tension (0 –
1 kV
inclusive) 0,1734 0,4161 0,8202 0,4161 0,1500 0,3119 0,1500 0,4970 0.1616 0,1500 0,7049 0,3928 0,1847
Medium
tension (1 –
110 kV
exclusive) 0,3235 0,1500 0,2425 0,1500 0,3928 0,1271 0,1500 0,5546 0,3119 0,1387

Tariff CI – monomial type with intake included
Tension level Subscriber(lei/day) Energy
price(lei/kWh)
1 2 3
Low tension (0 -1
kV inclusive) 0,4130 0.3119
Medium tension
(1-110 kV
exclusive) 0,3685 0,2425 Season Rush zone Gap zone Normal zone
Summer 8:00-9:00 00:00 -8:00
21:00 -00:00
and from Friday 21:00 till Monday 08:00 09:00 -21:00
Winter 8:00-10:00
19:00 -22:00 00:00 -8:00
21:00 -00:00
and from Friday 21:00 till Monday 08:00 10:00 -19:00

5.3.2 Annual energy covered by solar and auxiliary source
Kairos CF 2.0 (η=70%)
The monthly energy requirement for domestic hot water preparation
EM = E D x N [kWh / month]
ED = 107.5 kWh / day (daily energy requirement for domestic hot water ), N = no. of days
in the month
The monthly thermal energy obtained through the conversion of solar energy
ETM = S CST x E SD x N x η [kWh / month ], SCST=35 m2 (collector area),
ESD = solar energy available daily, η = 70% (conversion efficiency)

N EM ESD ETM Eaux CEE
Month Days kWh/month kWh/day kWh/month kWh/month Euro/kWh/month
January 31 3332 1.54 1170 2162 200
February 28 3010 2.29 1571 1439 133
March 31 3332 3.30 2506 826 76
April 30 3225 3.89 2859 366 152
May 31 3332 4.74 3600 0 0
June 30 3225 5.05 3711 0 0
July 31 3332 5.21 3957 0 0
August 31 3332 4.75 3608 0 0
September 30 3225 3.56 2617 608 56
October 31 3332 2.46 1868 1464 135
November 30 3225 1.56 1147 2078 192
December 31 3332 1.24 942 2390 221
Total 365 39234 29556 11333 1165

Amorti zation period of the solar thermal system
CII = Costs with initial investment, E A = annual energy requirement for DHW,
E = E TM monthly thermal energy obtained by converting solar energy
ES = energy saving
EEE = savings due to non -use of electricity energy
CEE = costs of auxiliary energy for the use of electricity
AEE = depreciation of the CST system taking reference price of electricity
Collecto
r area Initial
cost
investmen
t Necessar
y annual
energy
for water
heating Annual
energy
produce
d from
CST? Energy
savings Annual
savings Auxiliary
energy
cost Amortizatio
n
Scst CII EA ETM ES EEE CEE AEE
m2 EUR kWh/an kWh/an kWh/a
n EUR/Yea
r EUR/Yea
r Years
0 0 39234 0 0 0 3627
35 14287 39234 29556 29556 2733 895 5.2

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