M. A. Akintunde

Bio: M. A. Akintunde is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 13 citations.

Effect of Coiled Capillary Tube Pitch on Vapor Compression Refrigeration System Performance.

Abstract: The effects of various geometries of capillary tubes has been investigated by many researchers. Their studies were based on the coil diameters and lengths alone, with no particular attention placed on the effect of coil pitch. At present no information is available about the effects of serpentine coiled capillary tubes on refrigerator performance. This study examined the effects of pitches of both helical and serpentine coiled capillary tubes on the performance of a vapor compression refrigeration system. Several capillary tubes of equal lengths (2.03 m) and varying pitches, coiled diameters, and serpentine heights were used. Both inlet and outlet pressure and temperature of the test section (capillary tube) were measured and used to estimate the coefficient of performance (COP) of the system. The results show that, in the case of helical coiled geometries the pitch has no significant effect on the system performance but the coil diameter as already predicted by many researchers. In the case of serpentine geometries both pitch and height affects the system performance. Performance increases with both increase in the pitch and the height. Correlations were proposed to describe relationships between straight and coiled capillary tube and between helical coiled and serpentine coiled capillary tubes. The coefficient of correlations are: 0.9841 for mass flow rates of helical and serpentine with straight tubes; 0.9864 for corresponding COPs and 0.9996 for mass flow rates of serpentine and helical coiled tube.

Refrigeration And Air Conditioning

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An experimental study of the Effect of capillary tube diameter and configuration on the performance of a simple vapour compression refrigeration system

Abstract: The study of the expansion device in the simple vapour compression refrigeration system is necessary in order to understand the parameters which can enhance the overall performance of the system. The experimental study was done on the capillary tubes of 31 gauge, 36 gauge and 40 gauge and each test section was studied with three distinct configurations i.e. helical coiled, straight coiled and serpentine coiled configuration. The effect of the configuration and the capillary tube diameter on the overall performance of the system was studied. The findings of the experimental study revealed that the mass flow rate is maximum for the straight configuration and is least for the helical coiled configuration. The refrigeration effect was found to be maximum for the helical coiled configuration and was found to be least for straight coiled configuration. The compressor work was found to reduce as the load was increased on the system. Decreasing the capillary tube diameter increased the mass flow rate in the system and decreased the refrigeration effect produced.

Validation of a vapour compression refrigeration system design model

Abstract: This paper presents the validation of a design model for vapour compression refrigeration systems developed by Akintunde (2004a). This model was used to design a vapour compression refrigeration system. The experimental set-up is made up of: a compressorreciprocating type, 0.746 kW capacity, using R134a as working fluid, with cylinder stoke volume of 32.7 cm; evaporator and condenser, bare coil tube-in-tube serpentine copper coil. The cycle performance was evaluated through the following parameters; Cooling load (Qe); Condensing load (Qc); Coefficient of performance (COP) and mass flow rate. The R values (calculating using excel) of the COPs under subcooling and superheating with the degree of subcooling and superheating conditions were 80.7% and 88% respectively. While the correlations between the COPs under the same conditions were 88% and 99.9%. The present analysis showed that the model results are comparable to the actual system from both quantitative and qualitative points of view. Under the same operational conditions, maximum absolute deviations of the variable parameters – mass flow rate, COP and circulating water temperature, are within the range of 16%.

An Experimental Investigation and Performance Evaluation of 1.5 TR Window Air-Conditioner by Using R22, R407C and R410A by Varying the Capillary Pitch

Abstract: Due to ecological problems like Ozone depletion and Global warming certain refrigerants like R-22 have to be replaced. HCFC's (Hydro Chloro fluoro carbon) have been identified as the prime foremost cause of Ozone depletion. Driven by 1992 amendment to the Montreal-Protocol that calls for the phase out of HCFC's. HFC's (Hydro fluoro carbon) are substantially less damaging to the Ozone layer than HCFC's. Several refrigerants have emerged as substitutes to replace R-22, the most widely used Fluoro carbon refrigerant in the world. These include the environmentally friendly hydro carbon refrigerants such as R134a, R410A, R407A and R407C. In this present work problem of R-22 phase out in air conditioning application is addressed. The main objective of the project is Performance analysis of an window air conditioning system by using three refrigerants like R-22, R407C and R410A with different capillary pitches. In view of this it is proposed to carry out a number of experiments on window air conditioner of capacity 1.5 TR using R22, R407C and R410A by varying the capillary pitch. Further it is proposed to make a detailed analysis and comparison of the performance of these refrigerants at various pitches for an window air conditioner. From the results it is evident that the refrigerant with R410A with a capillary pitch of 18mm gave the best Coefficient of performance to retrofit an window air conditioner working on R22.

Effect of capillary tube on the performance of a simple vapour compression refrigeration system

Abstract: It is essential to study the effect of capillary tube geometry on the performance of refrigeration systems. The literature review focuses on the effect that geometrical parameters like capillary tube length, bore diameter, coil pitch, number of twist and twisted angle have on the pressure drop, coefficient of performance (COP) and mass flow rate of the system. These parameters can be further studied using physical models and mathematical modeling concepts. The parameters stated above can be further optimized in order to enhance the performance of the refrigeration system.