National Conference on Recent Trends in Engineering & Technology
SOLAR ENERGY ASSISTED ICE PLANT
Prof. R.S. Bhatt
Mechanical Engineering Department,
Birla Vishvakarma Mahavidyalaya (Engineering College)
Vallabh Vidyanagar
Gujarat.
Email: [email protected]
Deval Dixit
Mechanical Engineering Department,
Birla Vishvakarma Mahavidyalaya (Engineering College)
Vallabh Vidyanagar
Gujarat.
Email: [email protected]
Abstract— Energy conservation and use of the renewable
sources of the energy in most efficient manner is the main
challenge faced by the engineers in today’s world. Energy
conservation can be implied strongly only if the energy is
utilized in the optimum manner. To fulfill the increasing
amount of the energy ,conservation of the energy is very
important. So only where ever possible we should use the non
conventional sources of the energy. With this idea we entered
in thinking about ice plant. Here we have made an attempt to
design the ice plant operating with solar energy. Presently in
industrial field the ice plants are operated using compressors
which consume large amount of the electrical energy. As per
one survey it is estimated that out of total electricity utilized,
15% goes for the purpose of refrigeration. So if we are able to
make our refrigeration system work on solar energy, lot of
saving of energy can be done. Here we have tried to use solar
energy for producing ice in an ice plant.
I.
INTRODUCTION
The first recorded solar-driven machine was in 1872 by Albel
Pifre, in Paris, for producing a small amount of ice. In the
beginning of the 20th century, many countries were interested
in using solar energy, but the technology was focused only on
the heating of water or air. Research in ‘solar air-conditioning’
increased only after 1965. During the first oil crisis in 1973,
the air conditioning system was considered as a luxury and an
unnecessary system. The attention was focused on
improvement of design and efficiency of the refrigeration
system rather than investigation of it as a novel system. The
solar energy is the everlasting source of energy and our
country’s geographical location allows tremendous scope of
utilizing the solar energy. Many countries have funded
research and development project, in order to develop
commercial units as an alternative of continuing the
dependence on the use of conventional fuels. The world
started searching for new energy sources. But the same can be
viable only if 1) Its availability is in abundance 2) It can be
harnessed as per need 3) It is economically viable
13-14 May 2011
Siddharth Raghavan
Director,
Mamata Energy Ltd.,
Ahmedabad
Email: [email protected]
Suraj Andharia
Mechanical Engineering Department,
Birla Vishvakarma Mahavidyalaya (Engineering College)
Vallabh Vidyanagar
Gujarat.
Email: [email protected]
The use of solar energy can be made in many fields like water
heating, space cooling, space heating, electric conversion,
power generation, distillation etc. Now, here we have tried to
work on producing refrigeration using solar energy. We have
done analysis of ice plant and represented here its functioning
using solar energy with all the required data. Here we selected
the ice plant of fixed capacity. The enthalpy drop taking place
at the various components is found using enthalpy
concentration chart. On completion, we were able to find out
the amount of energy needed to be supplied in the generator
by the solar energy source. To collect this energy various
components like the solar collector, storage tank, and manifold
are used. The type of collector used is evacuated tube collector
as it will give us the temperature of water around 85˚C. Due to
the collector efficiency and storage efficiency the net amount
of heat produced is more than that required in the generator.
This system being practically possible to be operated by the
solar energy, its only drawback is that its initial cost is very
high. But with the increasing demand of such products and
government support provided on such innovative products,
will help to decrease the initial cost of the product. Besides
this, its easy and free availability and pollution free nature
makes its use for the refrigeration very effective.
II.
USE OF SOLAR ENERGY FOR REFRIGERATION
To use the solar energy for the purpose of refrigeration, there
are two ways in which the solar energy can be used:
1) Converting solar energy into electrical energy and use the
same for refrigeration
2) Directly using the heat energy for refrigeration.
So many refrigeration cycles are available for producing
refrigeration, but for our application of ice plant, we require
either VCR or VAR system to be operated. Hence for
selecting one of the two cycles, comparison is made between
the two to find best suitable refrigeration cycle for our “Solar
Energy Assisted Refrigeration”.
B.V.M. Engineering College, V.V.Nagar,Gujarat,India
National Conference on Recent Trends in Engineering & Technology
III.





COMPARISION BETWEEN VCR AND VAR
In VCR system, compressor is used. It consumes
more electrical energy as it has to work against large
decrease in volume of refrigerant. For e.g. vapour
refrigerant at 0.0061 bar has a volume of 206.31
m3/kg and when compressed to 0.07375 bar its
volume has to be decreased to 19.546 m3/kg. So,
large electrical energy will be required.
Maintenance of VAR is less, as there is only one
moving part & others are steady parts. Pump does not
consume more power like compressor.
VAR system is not dependent on the increase or
decrease in evaporator pressure because it can be
adjusted easily by increase or decrease in the
generator temperature.
Quality of refrigerant leaving the evaporator in VCR
system is important as compressor cannot compress
liquid while it is not so important in VAR system as
absorber is there.
As shown below if VCR has to be operated, solar
energy has to pass through many conversions and
loss increases.
Solar
→
Energy
Heat → Electrical
Energy Energy
Up till here this was the basic information of the systems
which will be used in solar energy assisted refrigeration. Now
assuming that a vendor in GIDC needs to supply 10 tonnes of
ice per day, and he is interested in doing it using solar energy,
how can he do it?
He has to first find the enthalpy drop at evaporator, absorber,
generator, and condenser. From this, he will be able to know
the heat needed to be supplied to the generator. This heat to
the generator will be given by solar energy.
→ Mechanical
Energy
While in VAR only one conversion from solar to
Thermal energy takes place.
Solar → Heat
Energy
Energy

VCR cycle requires photovoltaic cells, which are
costlier as compared with the solar collectors.
IV.
VAR SYSTEM OF AQUA – AMMONIA
In our application we have selected the VAR cycle working on
the aqua ammonia pair.
Some substances have more affinity for another substance at
desired temperature and pressure. This principle is used in
working of VAR system.
It is one of the refrigeration systems which mainly use heat
energy instead of mechanical work. Its main components are
generator, condenser, absorber, evaporator, pump etc.
Here one fluid is used as the refrigerant, while the other fluid
is used as absorbent. Ammonia is used as refrigerant and water
as absorbent. With ammonia as refrigerant we can attain much
lower temperature. The compressor of VCR is replaced by
generator, pump, absorber, and liquid throttle valve.
In this project as discussed earlier we are going to replace this
VCR system by VAR.
The water is made to flow surrounding ice cans. This water
has salt dissolved in it to decreases the freezing point of the
water and takes it up to -8˚C. This water gets cooled as it
passes through the space surrounding the evaporator tubes.
This cooled water will in turn produce ice in cans.
13-14 May 2011
V.
CALCULATION FOR SOLAR ENERGY ASSISTED
ICE PLANT
Suppose we want to produce ice from water at (30˚C) to ice at
(-5˚C). This is our aim on which complete design of VAR
system is based.
Calculations:Total Energy required to be extracted from water is
= 30˚C – 0˚C + 0˚C – 0˚C + 0˚C – (–5˚C)
Water
Water – Ice
Ice
= (m Cp ∆t)
Water
+
ENTHALPY +
Fusion
(m Cp ∆t)
Ice
= (1000kg * 4.187 kJ/kg K *30K) + 335*1000 kJ + (1000 *
1.94 * 5)
= 470280 kJ
For 10 tonnes of ice = 10*470280 =4702800 kJ
So refrigeration capacity = 4702800/ (24 * 3600) =54.43
kJ/S capacity in TR = 54.43/3.5 = 15.55 TR
So to produce 10 tonnes per day we require system of 15.55
TR capacities. Now to produce this much TR using NH3-H2O
system, we need to design the appropriate VAR system.
B.V.M. Engineering College, V.V.Nagar,Gujarat,India
National Conference on Recent Trends in Engineering & Technology
Here we are going with certain assumptions in designing VAR
system, while the evaporator and condenser condition are
known
Plant capacity = 15.55 TR
Condenser temperature = 30˚C and corresponding pressure is
12 bar
Evaporator temperature = –5˚C and corresponding pressure is
3.5 bar
Concentration of strong solution leaving the absorber = 0.4
Temperature of aqua ammonia leaving the generator = 85˚C
Now based on this, we used the enthalpy concentration chart.
We were able to find the enthalpy drop across various
components and the mass flow rate too.
After finding the enthalpy drop across each component we
multiplied it by mass flow rate to get the energy required in
that section...by this way we got the energy required to be
given in the generator
Mass flow of refrigerant (m)
= Capacity / RE
= 0.05 kg / s (obtained by doing calculation)
So, we get heat required to be given in generator
Qg = 116.5 kW
So, our interest lies in that 116.5 kW. Nowadays this energy is
supplied with the help of fuel like petrol, diesel and even coal
and kerosene. Theses are all going to vanish one day, so
instead of this thing if we use something that is permanent and
not harmful to human being, than there cannot be another
option better than solar energy. So if we are able to supply this
116.5kW energy with help of solar energy, than “solar energy
assisted refrigeration” will truly come into existence. But now
the question comes how to collect the solar energy? In which
form to collect the energy and in which form supply it to the
generator?
VI.
EVACUATED TUBE COLLECTORS
There are many ways to collect the solar energy. We need to
find out how many pipes are needed to produce 116.5kW. But
we need to supply 116.5kW in generator. But the hot water
comes in the generator through hot water tank, which has the
efficiency of 85%. The water enters the hot tank through
manifold, in which the heat is given to water by collector. The
efficiency of the collector is taken as 76%. For this we can use
flat plate collector, concentrated collector and recently
developed and most efficient the evacuated tube collectors
which can work in both direct and diffused sun light.
Temperature around 90˚c to 100˚c can be obtained. Vacuum
is maintained between outer pipe surface and inner plate:-Radiation loss α t4
Where t= temperature
As no air in between absorbing surface and surrounding,
radiation losses are minimized to a great extent. Our aim is to
achieve 80˚C-85˚C temperature hence for our refrigeration
purpose we select this collector. Before linking this collector
13-14 May 2011
with our VAR ice plant we need to know about the working of
the evacuated tube collectors.
The blue colour rectangular strip present in the middle is a
metal strip having coating of aluminum nitrate. It has a very
high absorbing capacity of almost 92% i.e. out of the entire
solar energy incident on it; it will absorb 92% of solar
radiation.
Between the rectangular strips there is a small cylindrical
copper tube. The heat absorbed by the aluminum nitrate will
be passed on to this copper tube. In this hollow copper tube, a
solution of propylene glycol is present, which on receiving the
heat from copper tube will evaporate.
The tubes are kept slanted, so the evaporated propylene glycol
will move upwards as this is the tendency of most of the gases.
This vapour propylene glycol reaches the heat pipe as shown
in the figure. At this end the water is passed through the heat
pipe which is at low temperature than that of vapour propylene
glycol. During the heat exchange propylene glycol losses
latent heat of vaporization and gets converted into liquid and
moves down the tube. This latent heat it received by the water
flowing and so temperature of water increases. This liquid
propylene glycol again gets heated and comes at top of the
heat pipe and same process gets repeated.
High efficiency is obtained by using powerful insulation like
glass wool and Rockwool.
So 180.34 ≈ 181 kw energy to produced.
Energy incident on earth surface is 500W/m2 to 1000W/m2.
Designing for worst condition i.e. for winter when sun
intensity is not large enough 500W/m2.
Selecting pipe of 2m length and 0.1m width
So energy produced by one pipe = 0.5 kW/m2 * (2 * 0.1)
2
m
= 0.1kW / pipe
So total number of pipe needed to produce 53kW is:
n = 181 /0.1
= 1810 pipes
Assuming each collector is made up of 20 pipes, total 91
collectors will be needed. By keeping these many collectors,
we will be able to operate our ice plant from 9 A.M to 6 P.M.
During the remaining time we must use some other source of
energy like kerosene, coal etc.
VII. ANGLE OF COLLECTOR
Collectors should be kept such that maximum absorption of
the sun rays is done by collectors. This is possible only when
sun rays are at 90˚ to the collector surface. Latitude indicates
the angle at which the sun rays are incident at a place. So if
collectors are kept at an angle equal to latitude of that place
than we will get maximum absorption of sun rays. VV Nagar
lies at tropic of cancer which is at 23.5˚. So to make this plant
in VV Nagar we have to keep collector at 23.5˚.
B.V.M. Engineering College, V.V.Nagar,Gujarat,India
National Conference on Recent Trends in Engineering & Technology
VIII. LIMITATION WHICH CAN BE OVERCOME
As discussed earlier, this plant will be in operation during day
time. But to operate this plant in the night time it will be
possible, if another circuit of solar system is kept similar to the
one discussed earlier. So to operate the plant in the night we
need to keep another solar collector of evacuated type only,
and use other two water tank. Advantage of this system is that
we will be able to make our system work for 14 – 15 hours.
Due to this, the operating cost will decrease as the
consumption of the conventional energy source like coal,
kerosene will decrease. The major disadvantage of this system
is that the initial cost due to 2 solar panels will increase.
Breakeven of this system will be around 7.79 years, means
after this many years we will be able to overcome our cost and
start earning profit.
IX.

CONCLUSION
This system is highly dependent on the cost of the
solar collectors. These collectors are produced in china,
and it is being imported to India. Due to this the cost of
the each collector is around 300 rupees. But in future if
production of these collector pipes is started in India than,
the cost of the pipe would come around to 170 – 200
rupees, and thereby decreasing the initial cost of the
installation
 The government policy influences the cost very
much. If the government provides proper tax
relaxation and subsidies for the products which are
using non conventional energy, than cost of the solar
energy assisted refrigeration will decrease.
13-14 May 2011

The system has still not been introduced in the
practice, so because of less consumption its initial
cost is high, but as the consumption increases its cost
will decrease.

The cost is also high because during the night time
we were using the conventional source of the energy.
So to decrease this cost it is also possible to use the
hybrid system, in which bio mass can be used to heat
the water. This alternative would be very much useful
to us, in making this system feasible.
REFRENCES
 Dr MOHANA SIR
( Sardar Patel Renewable
Energy Resources Institute )

SIDDHARATH RAGHAVAN SIR (Mamata Energy
Ltd.)

Ice Plant ( GIDC, Vitthal Udyognagar.)

Material by Prof. P.S. Desai and C.P. Arora
B.V.M. Engineering College, V.V.Nagar,Gujarat,India