Performance of Air Cooler and Heat Pump

PERFORMANCE OF AIR COOLER AND HEAT PUMP

Objectives:

To carry out the experiment with air cooler and heat pump and compare expected air condition with the real air condition measured using wet and dry bulb thermometers.

To evaluate the performance of the air cooler and heat pump at different working conditions

Introduction

The apparatus is an instrumented version of a commercial heat pump and air cooler. It has a heating or cooling capacity ranging from 1.5 kW to 3 kW depending on ambient conditions.

Air enters by way of a finned heat exchanger as shown in Figure 1. It is drawn in by a centrifugal fan which discharges to a circular duct at the backside as shown in Figure 2. When the air is cooled and the relative humidity rises, moisture is deposited on the heat exchanger and drained to a measuring vessel.

When the apparatus is working as a heat pump, drawing energy from the water and delivering it to the air, the compressor delivers refrigerant under pressure and at high temperature to the refrigerant to air heat exchanger. Heat is transferred to the air and the refrigerant condenses, passing through a reducing valve to the low pressure side of the circuit and thence to the refrigerant to water heat exchanger, where it evaporates and returns to the compressor.

When the apparatus is working as a cooler, direction of flow is reversed. In this case the air will sometimes be cooled to below the dew point and condensate will be deposited. The latent heat of this must therefore be taken into account in the energy balance. The coefficient of performance of the equipment depends on which mode it is operating as:

〖COP〗_R=Desired output/Required input=Cooling effect/Work input=Q ̇_L/W ̇_in (1)

〖COP〗_HP=Desired output/Required input=Heating effect/Work input=Q ̇_H/W ̇_in (2)

Fig. 1: Schematic diagram of PLINT TE94 Air Cooler

Fig. 2: Schematic diagram of PLINT TE94 Heat Pump

Experimental procedure:

Conduct the following experiment and tabulate the results on the