Air refrigeration system by Bell Coleman cycle and Vortex tube

My final year project

1. AIR REFRIGERATION SYSTEM BY USING BELL-COLEMAN CYCLE AND VORTEX TUBE By: Project Guide : E.Nikhil Kumar(12000T0338) Anil Kumar M.Aparna (12000T0304) P.Jagan (12000T0314) k.Sirisha (12000T0353) M.Ram Kumar(12000T0321)

2. Aim The aim of our project is to produce the refrigeration effect using both Bell-Coleman cycle and Vortex tube. In this project we mainly concentrated on the cold end temperatures of Vortex tube through which refrigeration effect is produced. We fabricated four different vortex tubes with different dimensions, number of nozzles, orifice & Venturi and compared their COP’s and cooling rates. Our project gives the scope of replacing conventional refrigeration systems with air refrigeration system

3. Introduction Air refrigeration system generally uses air as medium, whereas other refrigeration systems use refrigerants (Freon’s, ammonia etc.,) as medium. Since air is used as refrigerant no damage to atmosphere is done. By using other refrigerants damage to atmosphere such as ozone layer depletion takes place. Compression of air needs much power compared to compression of refrigerants. This system produces low COP because of which it has become obsolete. Other refrigeration systems have high COP but have severe impact on atmosphere. Moreover these refrigerants are too expensive and handling of these refrigerants is difficult .  

4. Bell-Coleman cycle refrigeration system Components of Bell-Coleman cycle refrigeration system : Air Compressor Heat Exchanger Air Regulator Evaporator (Cabin )

5. Working of Bell-Coleman cycle 1 . Isentropic compression process 2. Constant pressure cooling process 3. Isentropic expansion process 4 . Constant pressure expansion process

6. Working of Bell-Coleman cycle Isentropic compression process: The cold air from the refrigerator or atmosphere is drawn into the compressor cylinder where it is compressed isentropically in the compressor as shown by the curve 1-2 on p-v and T-s diagrams. During the compression stroke, both the pressure and temperature increases and the specific volume of air at delivery from compressor reduce from v 1 to v 2 . We know that during isentropic compression process, no heat is absorbed or rejected by the air. Constant pressure cooling process : The warm air from the compressor is now passed into the cooler where it is cooled at constant pressure P 3 (equal to P 2 ), reducing the temperature from T 2 to T 3 (the temperature of cooling water) as shown by the curve 2-3 on p-v and T-s diagrams. The specific volume also reduces from v 2 to v 3 .

7. 3. Isentropic expansion process : The air from the cooler is now drawn into the expander cylinder where it is expanded isentropically from pressure P 3 to the refrigerator pressure P 4 which is equal to the atmospheric pressure. The temperature of the air during expansion falls from T 3 to T 4 shown by the curve 3-4 on p-v and T-s diagrams. The specific volume of air at entry to the refrigerator increases from v 3 to v 4 . We know that during isentropic expansion of air, no head is absorbed or rejected by the air. 4. Constant pressure expansion process : The cold air from the expander is now passed to the refrigerator where it is expanded at constant pressure P 4 (equal to P 1 ). The temperature of air increases from T 4 to T 1 . This process is shown by the curve 4-1on p-v and T-s diagrams. Due to heat from the refrigerator, the specific volume of the air changes from v 4 to v 1 .

8. Apparatus required Digital Thermometers – 2 Copper tube (Heat exchanger) – 1 Air Compressor Air regulator Cabin Digital Anemometer Connecting pipes

9. Compressor

10. Heat Exchanger

11. Air Regulator

12. Cabin

13. BELL COLEMAN CYCLE EXPERIMENTAL SETUP

14. Procedure of experiment For different compressor pressures after expansion, We calculated the Cooling effects and COP’s by using evaporator’s inlet and outlet temperatures. We plotted the graphs for the same results 1) Pressure after expansion versus cooling effect 2) pressure after expansion versus COP

15. Working Video

16. Observations from Graphs It is found out that As inlet pressure increases, COP of Bell Coleman cycle increases. As inlet pressure increases, cooling effect of Bell Coleman cycle increases.

17. Results The Cooling effect of the Bell Coleman cycle is found out to be 0.011 KW The COP of the Bell Coleman cycle is found out to be 0.015

18. VORTEX TUBE The vortex tube is a structurally simple device with no moving parts that is capable of separating a high-pressure flow into two lower pressure flows with different energies, usually manifested as a difference in temperatures. The vortex tube is relatively inefficient as a stand-alone cooling device but it may become an important component of a refrigeration system when employed as an alternative to the conventional throttling valve.

19. Vortex tube working principle

20. Vortex tube has following parts: Air Inlet Vortex Chamber Hot end side Cold end side Hot end obstruction Construction details of Vortex tube

21. Air Inlet

22. Vortex Chamber Vortex chamber has nozzles for air to enter the chamber and an orifice

23. Vortex chamber

24. Orifice and Venturi

25. Nozzles

26. Hot end obstruction

27. Standard Dimensions Tube Inner diameter = D Nozzle diameter = D/8 Orifice diameter = D/2 Cold end length = 10D Hot end length = 45D We have varied these dimensions and fabricated four different vortex tubes and observed the COP’s and Cooling effects

28. Dimensions of fabricated Vortex tubes Tube inner diameter (small) – 13.5mm (Tubes 1 & 2) Tube inner diameter (Big) – 19mm (Tubes 3 & 4) Couplings Cold end lengths - 135mm, 190mm (rounded off a bit) Hot end lengths - 608mm, 855mm (rounded off a bit) Orifice diameter - 6.75 (Tubes 1 & 2) Venturi diameter - D = 19mm , d = 9.5mm

29. Vortex Tube – 1 (2 Holes, Orifice)

30. Vortex Tube – 2 (4 Holes, orifice)

31. Vortex Tube – 3 (2 Holes, Orifice)

32. Vortex Tube – 4 (4 Holes, Venturi )

33. VORTEX TUBE: The experimental setup of vortex tube air refrigeration system is same as Bell- Coleman cycle. The only change is heat exchanger is removed and vortex tube is added to the cycle E XPERIMENTAL SETUP Air compressor Heat exchanger Vortex tube Cabin

34. Vortex Tube Experimental set up

35. Digital thermometer

36. Digital Anemometer

37. Procedure of experiment For four different Vortex tubes which we fabricated, we calculated Cooling effects and COP’s at different inlet pressures. We also calculated mass flow rates and plotted graphs for 1) Mass flow rates versus Temperature difference 2) COP versus Inlet pressures and came at various conclusions.

38. Working Video

39. Temperature differences of 4 vortex tubes at different pressures

40. COP of 4 vortex tubes at different pressures

41. Observations After injecting the air at the different pressures, we found out the max difference in the temperature of the air at both the ends for our vortex tubes is around 35oC. This temperature difference is not noticeable or not as expected from the vortex flow tube. As vortex flow tubes generally give the difference around 70-80 0 C. It is observed that as the as the inlet air pressure of the vortex tube increases, the cooling effect also increases

42. Conclusions From the calculations it is observed that for the same power input, cooling effect produced and COP of the vortex tube is high compared with cooling effect and COP of Bell-Coleman cycle Of the 4 fabricated vortex tubes, Vortex tube 1 (internal diameter = 1.35 cm and 2 holes with orifice) has higher COP and cooling effect than others. COP of vortex tube 1 is 0.03574 at 6 kg/cm2 inlet pressure.

43. Comments One reason of our set up not giving temperature difference of 70-80 oC is the air leakage. Some amount of air was leaking from the compressor fittings, coupling of the pipes.

44. Advantages of vortex flow tube 1. It uses air as refrigerant, so there is no leakage problem. 2. There are no moving parts in the vortex tube 3. Vortex tube is simple in design and it avoids control system. 4. It is light in weight and requires less space. 5. Initial cost is low and its working expenses are also less, where compresses air is readily available. 6. Maintenance is simple and no skilled labour are required. 7. Very simple design can easily be made at home. 8. Can cool the fluid up to 4 0C.

45. Disadvantages 1. Its low COP 2. Limited capacity. 3. Small portion of the compressed air appearing as the cold air limits its wide use in practice.

46. Applications 1. Vortex tubes are extremely small and as it produce hot as well as cold air. It may be used in industries where both are simultaneously required. 2. Low temperatures can be obtained without any difficulty, so it is very much useful in industries for spot cooling of electronic components. 3. It is commonly used for body cooling of the workers in mines.

47. Future scope By using continuous discharge compressors (vane type or gear type) we can get continuous and high air pressures. Because of which high cooling effect and COP can be achieved for both Bell-Coleman cycle and Vortex tube air refrigeration system. By using high capacity Vortex tubes, high cooling rates by Vortex tube air refrigeration system can be achieved. By sending the air at high pressure and low temperature into Vortex tube, even low cold end temperatures can be achieved.

48. References Sl.no Paper Author 1 Review on Vortex tube Refrigeration Rahul Dilip Pawar N.C.Ghuge 2 The Application Of Vortex Tubes to Refrigeration Cycles. G. F. Nellis S. A. Klein 3 Experimental Performance Study of Vortex Tube Refrigeration System Sankar Ram T Anish Raj K 4 Performance Analysis of a Vortex Tube by using Compressed Air Ratnesh Sahu , Rohit Bhadoria , Deepak Patel 5 An Experimental Setup of Vortex Tube Refrigeration System Karthik S

49. Sl no paper Author 6 Vortex tube refrigeration system Based on Compressed air. Tejshree Bornare , Abhishek Badgujar , Prathamesh Natu 7 Experimental Investigation of Vortex Tube Refrigeration. Sarath Sasi1, Sreejith 8 Experimental study of Bell Coleman cycle using Air as Refrigerant P.V.Ramana 9 Performance evaluation of refrigeration system based on Bell coleman Cycle Rahul Patel Ramji Tripathi

50. Otto Belden blog on Construction of vortex tube Various youtube videos various articles about vortex tube on google Wikipedia

51. THANK YOU 