IJCRR - Vol 03 Issue 09, September, 2011
Date of Publication: 30-Nov--0001
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EFFECT OF FRICTION FACTOR ON THE PERFORMANCE OF ADIABATIC CAPILLARY TUBE
Author: Rahul Gulati, R.C.Gupta
Abstract:In this paper analysis the performance of capillary tube under the different condition. The following
condition are : condensing temperature 40-55?c , subcooling 0-5?c , capillary tube diameter 1.2 \? 2.4mm ,
mass flow rate 5 \? 50 g/s , various friction factor given by different authors is used to predict the
performance of capillary tube with R-22 , R-134a , R-410A refrigerant.
Keywords: Capillary tube; Adiabatic; Alternative refrigerant; Friction factor.
A typical residential air conditioner consists of a compressor , evaporator , condenser and expansion devices. Capillary tubes is one of the expansion devices has been extensively used for the past flow decades. Now a day electronic expansion valves and / or short tube orifices are considered as future expansion devices for some what large size air- conditioners heat pump. HCFC 22 has been used superior as the working fluid in residential air conditioners due to its excellent properties and fit for combining with various materials. HCFC 22 contains hydrogen and chlorine atoms and its ozone depletion potential is 0.05. Since HCFC 22 has the ozone depleting chlorine it is to be phased out eventually according to the montreal protocol amendments adopted by the participating countries . The alternative of HCFC 22 are HFC 134a , R-407C (23% R-32/25% R- 125/52% HFC-134a) and R-410A (50%R- 32/50%R-125).
In this paper, the performance of adiabatic capillary tubes used is predicted for R-22, R- 134a , R-410A. The following conclusions can be drawn.
(1)Duckler‘s equation is not better than McAdams‘ equation for two -phase viscosity calculation.
(2) Kinetic energy term in energy conservation equations is not impacting on the final results.
(3) pressure drop due to area contraction is impacting on the model so it needs to be considered in the model.
(4) Refrigerant R-134a show the optimum length as compare to others refrigerant for the given condition.
(5) From the above analysis for predicting the performance of capillary tube Hopkins  friction factor gives optimum result under the all conditions.
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2. Stoecker WF , Jones JW. (1982) Refrigeration and air conditioning. 2nd ed. McGraw Hill. p.260±72.
3. Melo c, Ferreira RTS, Boabaid Neto c, Goncalves JM, Thiessen MR. (1994) Experimental analysis of Capillary tubes for CFC-12 and HFC-134a. p.347±52.
4. Hopkins NE. (1950) Rating the restrictor tube method of determining flow capacities for Freon-12 and Freon-22. Refrigerating Engineering 58(11) : 1087± 95
5. Collier Gj ,Thome JR. (1996) Convective boiling and condensation. 3rd ed. UK : Oxford University press, p.110±11