4. OUR IDEA
By introducing an heat exchanger, we
would be able to recover the
superheat of the refrigerant gas for the
purpose of heating water.
5.
6. MATERIAL USED
1. In evaporator and heater, we used copper tube in coil shaped and
inserted it into water in a vessel of 4 litre capacity.
2. Compressor of 1/8 ton capacity.
3. Capillary of 1mm diameter and 1.5 m length.
4. R134a refrigerant of 465 grams.
5. Copper tubing of ¼ inch and 70 foot length.
6. Drier
7. FABRICATION
1. We bent copper tube in ‘coil shaped’ by wounding around different
sized containers for different diameter.
2. We have got made a cast iron stand from a known blacksmith.
3. We made proper arrangement for fitting of the compressor.
4. We made hook so that condenser can be properly fitted.
5. We also made ring arrangements for the containers so that they
may properly fitted get into it.
6. We made holes on both containers of ½ inch diameter with help
drill bit (hole saw cutter) and fitted tap with barrel foot pipe outlet
and applied waterproof m-seal, PVC solvent and checked for
leakage if any. We also made holes on upper side of container for
copper tubing inlet and outlet.
8.
9.
10.
11. BRAZING
Brazing is done for the connection of parts by means of copper
tubes. For brazing, we had increased the diameter on one end of the
copper tube and inserted the second tube into it followed by
polishing of the upper surface of the joint tube. With the help of
brazing torch, we heated the joint till it appeared to be red hot and
heated the filler rod simultaneously. The filler rod started to melt and
we allowed it to drop on the joint. It got stuck to the joint and we
allowed for cooling for a while.
12.
13. GAS FILLING
We had done gas filling with the help of our experienced classmate,
Sadiq Fakih. We had used set vacuuming method in which one of
the two ends of the drier is kept open and the compressor is started,
thereby, the air inside the circuit goes out. After that, we closed that
one end while the compressor is still running for the pressure to
build inside the circuit. Before closing the open end, we filled the
refrigerant gas inside the circuit through the gas filling port of the
compressor at the required quantity and then closed the gas filling
port with help of a small non-return valve.
14. LEAKAGE TEST
After gas filling, we carried out the leakage test by running the
compressor for some time. During the leakage testing, we heard
many sounds of gas leaking at various joints in the circuit. To get a
proper insight of the leakages, we used soap-foam method to find
out where exactly the leakage was. After the detection of the
leakages at various joints, we carried out the brazing operation at
those areas.
15. PERFORMANCE TESTING
Energy consumption and work done by the compressor:
Time taken 3 impulse = 24 seconds
Energy meter constant (EMC) = 3200 impulse/kW hr
Therefore, energy consumption by the compressor,
Es = No. of impulse × 3600
Time taken for impulse × EMC
= 3 × 3600
24 × 3200
= 0.1463 kW
16. Let us assume that the mechanical efficiency of the compressor is 85 %.
Work done by the compressor (W) = Energy supplied × compressor efficiency
= 0.1463 × 0.85
= 0.119 kW
Mass calculation:
Mass capacity of chiller:
Volumetric capacity of chiller = 4 litres
We know, 1 litre = 10-3 m3
Therefore, 4 litres = 4 × 10-3 m3
Mass capacity of chiller, Mwc = 4 × 10-3 × 103 kg
Therefore, Mwc = 4 kg
Mass capacity of heater:
Volumetric capacity of heater = 4 litres
As both the containers are similar, therefore,
Mwh = 4 kg
17. COP calculation:
COP calculation by considering only cooling effect:
Time taken for the test = 30 minutes
= 30 × 60 seconds
= 1800 seconds
Tc1 = 35 C
Tc2 = 23 C
Refrigerating effect (RE) = Mwc × Cpw × (Tc1 – Tc2)
T
= 4 × 4.184 × (35-23)
1800
= 0.1115 kW
COP actual = RE
W
= 0.1115
0.119
= 0.937
18. COP calculation by considering heating and cooling effect:
Time taken for the test = 30 minutes
= 30 × 60 seconds
= 1800 seconds
Th1 = 30 C
Th2 = 40 C
Heating effect (HE) = Mwh × Cpw × (Th2 – Th1)
T
= 4 × 4.184 × (40-30)
1800
= 0.0929 kW
COP actual = HE + RE
W
= 0.0929 + 0.1115
0.119
= 1.717
19. COP difference due to waste heat recovery:
COP difference due to waste heat recovery = 1.717 – 0. 937
= 0.781
20. CONCLUSION
We get heating of 10 C and cooling of 12 C after 30 minutes. So,
our purpose of waste heat recovery by simultaneously heating and
cooling completed. We can use this hot water for dish washing, cloth
washing, bathing etc. Our college canteen can use this system for
simultaneously heating tea, coffee, water and chilling fruit juice,
water, cold drink etc. By considering heating as well as cooling
effect, our actual COP was also increased by 0.781.
