Refrigeration tubing is used in a domestic air conditioning system. In one such installation, a standard...

 

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Refrigeration tubing is used in a domestic air conditioning system. In one such installation, a standard copper tubing (K = 231 Btu/hr ftR, R = 0.044 ft, R2 = 0.0469 ft) is soldered in place from the compressor/condenser unit outside the building to the expansion valve/evaporator unit in the attic. The refrigerant keeps the inside wall of the tubing at 40F. In order that little heat is gained through the tube wall, it is covered with a sponge type of insulation that is inch thick and has a thermal conductivity of 0.02 Btu/hr ftR. The outside surface temperature of the insulation is 70F. Determine the heat gain per unit length of tubing. (Use thermal-resistance approach.) Refrigeration tubing is used in a domestic air conditioning system. In one such installation, a standard copper tubing (K = 231 Btu/hr ftR, R = 0.044 ft, R2 = 0.0469 ft) is soldered in place from the compressor/condenser unit outside the building to the expansion valve/evaporator unit in the attic. The refrigerant keeps the inside wall of the tubing at 40F. In order that little heat is gained through the tube wall, it is covered with a sponge type of insulation that is inch thick and has a thermal conductivity of 0.02 Btu/hr ftR. The outside surface temperature of the insulation is 70F. Determine the heat gain per unit length of tubing. (Use thermal-resistance approach.)