Experimental And Theoretical Investigation On Trans-Critical Carbon Dioxide Air Conditioning System And Its Heat Transfer Components

In this paper, the author investigates the characteristics of carbon dioxide(R744)-based air conditioning system and the heat transfer performance of its heat transfer components both experimentally and theoretically.A new wavy-perforated plate-and-fin surface is developed. Its heat transfer and pressure drop characteristics is tested by using steady method with infrared temperature measurement technique introduced. The experimental results show better performance of wavy-perforated surface than that of wavy surface when the Reynolds number is low.Temperature oscillation technique is extended to determine convective heat transfer coefficient in small ducts. An experimental system is built and experiments arc performed to measure convective heat transfer coefficient for supercritical carbon dioxide flowing in a small diameter round pipe and a multi-channel flat pipe under typical pressure and temperature conditions. The test results are compared with the predicted results by general correlation. The comparison demonstrates that the prediction based on general correlation is an acceptable approximation.It is proposed to use porou,s metal for carbon dioxide refrigeration and air conditioning heat exchangers to enhance their heat transfer. The single blow experimental system is set up to investigate the heat transfer characteristics of porous metal. The volumetric convective heat transfer coefficient is then measured for several typical porous aluminum samples which have high porosity. Non-dimensional heat transfer correlations are given.An experimental air-to-air trans-critical carbon dioxide air conditioning system is established. A dynamic simulation mathematical model and numerical algorithm are built. The relevant computer codes are then developed. Experiments and simulation under typical dynamic conditions are performed. The experimental and predicted results are compared and analyzed.