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Piping Design
Published in Herbert W. Stanford, Adam F. Spach, Analysis and Design of Heating, Ventilating, and Air-Conditioning Systems, 2019
Herbert W. Stanford, Adam F. Spach
To prevent this problem, the compressor must be provided with controls to minimize refrigerant migration to the crankcase during shutdown. One method is to use a liquid line solenoid valve and pump down control. A variation of this method is a combination of single pump down at shutdown, plus a crankcase heater. A third method is to energize a crankcase heater whenever the compressor is inoperative. The crankcase heater, by keeping the oil-refrigerant temperature at an elevated level, reduces the ability of the oil to attract and absorb refrigerant.
Validated air handling unit model using indirect evaporative cooling
Published in Journal of Building Performance Simulation, 2018
F. Jorissen, W. Boydens, L. Helsen
The computations of and were already discussed. was chosen equal to the data sheet value of 770 W. Using electrical power consumption measurements the stand-by power consumption was found to be 150 W when the unit is off. According to the manufacturer, typically 75 W is consumed by the compressor crankcase heater when the compressor is off, which accounts for half of the AHU stand-by power consumption. When the unit is on, the zero load power consumption was estimated by performing an experiment where Pa such that the fan power consumption was as low as possible. The fan power consumption was then computed using the measured mass flow rates, measured damper positions and the pressure drop model. The difference between the measured and simulated electrical power was found to be 630 W. Based on the data sheet the electrical drive losses at 20% nominal load are 375 W per drive. A large fraction of this 630 W may therefore be the zero load power consumption of the electrical drives.