High Efficiency Compressor-Condenser in a Single Hermetic Component for Heat Pumps

A unit that encloses a motor-compressor and a condenser of refrigerant fluid in a single hermetic casing is presented. After a description of the general advantages of the component compared with the traditional solution, as far as weight, size, cost and very low noise emission are concerned, experimental test results are presented. COP values in different working conditions show that a good energy performance is achieved making this component utilization attractive in the heat-pump field. INTRODUCTION In a vapor compression cycle the four basic operations (compression, condensation, isoentropic expansion, evaporation) are carried out by devices that, in most of systems, are single parts connected with each other in a loop on assembly lines. We have considered it could be of interest to make a single hermetic component containing both the compressor and the condenser of working fluid. Therefore, we have made a component which, in a cross section, appears as shown in Fig. 1. Between the two casings (see Fig. 1) we have put a formed coil working as condenser. Cooling of condenser is done by water flowing inside the coil. This integrated component should offer 101 Fig.1 First prototype the following advantages in comparison with the traditional solution (compressor plus separate condenser). Good use of material in assembly. This comes from the fact that the external surface of the compressor works also as casing surface of the heat-exchanger (copper tube casing). Reduction in weight This is an obvious consequence of the reduction in material usage. Reduction in dimensions This solution is of course more compact in comparison with two separate components. Easier assembling and handling From the final user's point of view, the connections necessary to set up a system in assembly lines are reduced and the handling involves a single component only, instead of two. The above-mentioned general features give to the component an interest from a potential savings point of view, but the most important aim of this prototype realization was to achieve better energy performances. The better energy performances due to: Heat recovery from compressor With the integrated compressor condenser, all the heat usually lost from compressor can be recovered. In fact, compressor cooling is guaranteed by the water flowing inside the heat-exchanger and the external casing can be thermally insulated. The heat usually lost from this size of compressor in normal working conditions can be evaluated and experimentally tested in 70/90 watts. The heat recovery in this way gives a gain thermal capacity and then of COP of 6-12%. Less superheating of suction gas This is due to a reduction of inner surface temperature of the compressor casing. The temperature nf the compressor casing decreases approaching values near to condensing temperature due to the presence of liquid refrigerant and the cold wall of the heat-exchanger. The suction gas, during its passage through the compressor, reduces its final superheating, so improving the compresCOP 5