A concept of evaporator aided by capillary effect

Abstract

Development of devices with reduced pumping power is gaining significant attraction recently. One of the examples are Organic Rankine Cycles which prove to be an attractive perspective for production of electricity and heat in the distributed generation. Actually the pumping power in such systems is very significant. In some cases it can reach up to 30% of generated power by the system. Hence reduction of pumping power is very tempting. Such possibilities are offered by application of the porous structures to aid the fluid motion. In the paper is presented an experimental facility designed for studies of the capillary effect in tubes made of porous media together with the results of commissioning tests. Examined are two fluids, namely ethanol and water, at three different fillings and three different evaporator temperatures. The results in the form of pressure distribution with time have been presented. The potential application of such effect is for example in the evaporator of the domestic micro CHP unit, where the reduction of pumping power could be obtained. Preliminary analysis of the results indicates water as having the best potential for developing the capillary effect. The net effect obtained in the facility was approximately 22hPa in pressure difference has been obtained for studied porous material, namely the sintered tube from stainless steel powder with the average pore-size of 3 micrometers.