Abstract
The air cycle heat pump, using air both as working medium and as heat carrier, and suggested by Lord Kelvin nearly 100 years ago, has advantages as a means of combined heating and ventilating, on account of its simplicity and the recovery of ventilation heat losses.
The paper briefly examines the theoretical possibilities of the air cycle for space heating and air drying. While the ideal air cycle is highly efficient with perfect machines, the inefficiency of actual machines and the temperature difference and air pressure drop across the heat exchanger reduce the performance considerably; but the power consumption for the net heat load is appreciably less than that for direct electric heating, whilst ventilation—for which electric heating is less suited—is provided in addition. Thus for certain applications such as hospitals, hotels, and restaurants where the number of air changes is greater, the air cycle heat pump might have economic advantages. The need for the improvement of heat exchangers is indicated, and the possibility of replacing separate compression and expansion machines by a “pressure exchanger” is discussed.
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