Abstract
An experimental and theoretical works were carried out to model the wire condenser in the domestic refrigerator by calculating the heat transfer coefficient and pressure drop and finding the optimum performance. The two methods were used for calculation, zone method, and an integral method. The work was conducted by using two wire condensers with equal length but different in tube diameters, two refrigerants, R-134a and R-600a, and two different compressors matching the refrigerant type. In the experimental work, the optimum charge was found for the refrigerator according to ASHRAE recommendation. Then, the tests were done at 32˚C ambient temperature in a closed room with dimension (2m*2m*3m). The results showed that the average heat transfer coefficient for the R-600a was higher than the R-134a, so the length of the wire tube was longer with R-134a than R-600a. The pressure drop for the smaller tube diameter was higher than the other tube. The second law thermodynamic efficiency was higher for R-600a, which reached 41%. The entropy generation minimization analysis showed that the R-600a refrigerant type and smaller tube diameter are approached the optimum point.
Highlights
The static condenser is used due to its low cost and simple construction
Theoretical and experimental work will be used to calculate the heat transfer coefficient and pressure drop in the condenser in three regimes. It shows the different performances of the used different refrigerants and different tube diameters of condenser, to optimize the condenser required to remove heat from refrigerant to air. This will be done by finding the flow pattern type and selecting the governing equations to calculate the heat transfer coefficient and the pressure drop in a detailed manner as well as to calculate the length of the heat exchangers, but few were directed to the static condenser as follows:Ragazzi, and Pedersen, 1991 developed a computer simulation modeling to optimize the air-cooled condenser with the refrigerants R-12 and R-134a
The results indicated that the external heat transfer coefficient could rise by 14% in the case when the condenser was fully free and by 9% if the space between the condenser and wall-room was enlarged by 0.3 m
Summary
The static condenser is used due to its low cost and simple construction. its performance is affected by the environment and the other components of the system. Theoretical and experimental work will be used to calculate the heat transfer coefficient and pressure drop in the condenser in three regimes (superheated, saturated, subcooled) It shows the different performances of the used different refrigerants and different tube diameters of condenser, to optimize the condenser required to remove heat from refrigerant to air. This will be done by finding the flow pattern type and selecting the governing equations to calculate the heat transfer coefficient and the pressure drop in a detailed manner as well as to calculate the length of the heat exchangers, but few were directed to the static condenser as follows:Ragazzi, and Pedersen, 1991 developed a computer simulation modeling to optimize the air-cooled condenser with the refrigerants R-12 and R-134a.
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