Integrated hollow porous ceramic cuboids-finned heat pipes evaporative cooling system: numerical modelling and experimental validation

The work presented in this paper investigates design, computer modelling and testing of a sub-wet bulb temperature evaporative cooling system for space air conditioning in buildings. The target application of evaporative cooling technology is particularly for geographical regions with hot and dry climate. A laboratory prototype made of integrated finned heat pipes and a water filled hollow porous ceramic cuboids was been built and tested. The design exploits the high thermal conductivity of heat pipes as effective heat transfer device and the good wettability characteristic of porous ceramic material. Key thermal performance metrics of the prototype were modelled and validated experimentally under controlled laboratory conditions of temperature (30, 35 and 40 oC) and relative humidity (35 to 55%). Under typical dry climates conditions (ambient air dry bulb temperature of 35 oC and relative humidity of 35%), the measured supply air dry bulb temperature was 22.3 oC, which is lower that the ambient air wet bulb temperature, and maximum cooling capacity of approximately 196 W per unit surface area (m2) of wet porous ceramic cuboid. Furthermore, it was shown that the measured prototype cooler wet bulb effectiveness was 1.05 while the dew point effectiveness was 0.73