2016 Volume 41 Issue 229 Pages 47-56
Generally, indoor heat sources without human thermal load radiate to a relatively high temperature compared to indoor temperature in a fixed position. If the heat emitted from heat sources will be absorbed by chilled water having a similar indoor temperature in directly, it is possible to improve a thermal environment due to a decrease in the distribution of indoor temperature distribution. Furthermore, it is also possible to save HVAC energy by improving the COP (coefficient of performance) of a heat pump by using high-temperature chilled water. This study is a part of a research that plans to realize a "liquid-cooled air-conditioning system", which is embodied in the basic idea of indoor air conditioning. This study consists of several papers; however, this paper shows the heat dissipation characteristics from primary heat sources (LED lighting, personal computer) in an office. This analysis will be the basis for evaluating a thermal environment in a task space, and will be the foundation design data for developing a "liquid heat recovery unit" which is a part of a "liquid cooling air-conditioning system". Reviewed PCs included a laptop and a desktop, and LED lighting was evaluated as a type of recessed lighting. All of them are widely used today. The surface temperature distribution of the target equipment was measured, and the input electric power under the thermal condition was approximately 25°C in the chamber. Then, a coupled simulation of convection and radiation was carried out based on measured data. Analysis results calculated using CFD(computational fluid dynamics) simulation showed that heat dissipation characteristics from target equipment is composed of convection heat and radiation heat from the surface, exhaust heat from an electric fan, and infiltration through surface gaps, such as USB port and keyboard. As a result, the amount of surface heat dissipation emitted to the indoor environment from each target equipment is approximately 35~75% of the total heat transfer, and it is divided into 40% convection and 60% radiation.
