A cooling system is required to maintain an acceptable indoor temperature and provide heat rejection of...

 

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A cooling system is required to maintain an acceptable indoor temperature and provide heat rejection of 21,600 Btu/hr. The refrigerant in the condenser operates at 340 psi, corresponding to a saturation temperature of 125 °F. The ambient air temperature is 100 °F, and the flow area is 36 ft². The airflow treating the air flows through 0.25-inch diameter tubes, and the airflow rate is 8000 ft3/min. (Air properties: p = 0.015 lbm/ft³, cp = 0.29 Btu/lbm°F, 9 = 2.4 x 10!" ft²/s, k = 0.05 Btu/hr*ft*°F, Pr = 0.7), assume Nu-3.66 for laminar flow. Use a related equation to calculate Nu if it is turbulent. A) Based on the provided information, find the convection heat transfer coefficient (Btu/hr. ft². °F) for the air flow treating the air. B) Regarding your answer to part A, assume h_air = 10 Btu/hr*ft² *°F and C_min = 2000 Btu/hr F. Consider that this relatively low heat transfer coefficient will be the controlling resistance, then the overall heat transfer coefficient will be close (assume it is identical) to this value. Estimate the heat transfer surface area required using NTU method in units of ft². A cooling system is required to maintain an acceptable indoor temperature and provide heat rejection of 21,600 Btu/hr. The refrigerant in the condenser operates at 340 psi, corresponding to a saturation temperature of 125 °F. The ambient air temperature is 100 °F, and the flow area is 36 ft². The airflow treating the air flows through 0.25-inch diameter tubes, and the airflow rate is 8000 ft3/min. (Air properties: p = 0.015 lbm/ft³, cp = 0.29 Btu/lbm°F, 9 = 2.4 x 10!" ft²/s, k = 0.05 Btu/hr*ft*°F, Pr = 0.7), assume Nu-3.66 for laminar flow. Use a related equation to calculate Nu if it is turbulent. A) Based on the provided information, find the convection heat transfer coefficient (Btu/hr. ft². °F) for the air flow treating the air. B) Regarding your answer to part A, assume h_air = 10 Btu/hr*ft² *°F and C_min = 2000 Btu/hr F. Consider that this relatively low heat transfer coefficient will be the controlling resistance, then the overall heat transfer coefficient will be close (assume it is identical) to this value. Estimate the heat transfer surface area required using NTU method in units of ft².

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Explanation To find the convection heat transfer coefficient h for the air flow treating the air we ... View the full answer