K. H. Yang

An approach to building energy savings using the PMV index

Abstract The PMV index takes many factors into account in evaluating thermal comfort of indoor climate. The radiant temperature is a significant factor, especially in hot and humid areas, with the result that conventional indoor temperature and humidity control cannot guarantee indoor comfort. The indoor air velocity is a key factor which can reduce the cooling, and thus save energy. This approach is validated with a full-scale experiment.

An innovative analysis and experimental investigation on energy savings of a VAV system in hot and humid climates

Abstract An innovative calculation methodology is proposed in this paper which retains the accuracy of sophisticated computer simulation programs, such as DOE 2.1, but maintains the simplicity of simplified building energy calculation methods, such as the Modified Bin method. The entire calculation procedure is discussed and followed by a full-scale experiment on a VAV (Variable Air Volume) system which successfully demonstrated its effectiveness. This method is now proposed to be adapted as the main part of the national building energy code or PACS index in Taiwan.

Moisture migration and condensation within porous material

Abstract This paper is concerned with the analytical study of moisture diffusion, convection and condensation within porous material. Applying the concentration and energy balance principles, we describe the one‐dimensional steady‐state moisture migration through the porous material from one side exposed to a humid environment, and film condensation on the other side of the cold plate. The temperature at the condensation interface is calculated iteratively to yield the concentration and temperature profiles in the moist‐air region, and the film thickness and condensation rate in the condensate zone. Results are examined and discussed for typical porous insulation material and indoor conditions. Dependency on the critical relative humidity, above which condensation outside the liquid film region will occur, on the ambient temperature is presented in a psychrometric chart.

The analysis of a solar‐assisted desiccant evaporative cooling system and its application

Abstract The direct application of an evaporative cooling system is impractical in Taiwan due to local hot and humid weather conditions. In this study, a hybrid cooling system utilizing an evaporative cooler coupled with a chemical dehumidifier is investigated. The solid desiccant, or silica gel, which could be regenerated by solar energy, dehumidifies the incoming air while the evaporative cooler effectively cools it down to the indoor comfort condition. An optimal design approach including a sensitivity study was performed during the computer simulation process. A systematic result was obtained providing design information, such as the desiccant consumption rate and solar collector area needed for indoor comfort air‐conditioning.

An Experimental Analysis on Energy Savings of VAV Systems in Hot and Humid Area

Variable Air Volume (VAV) air-conditioning system presents great energy savings potential especially in hot and humid climate and has been recommended in the Building Energy Code of Taiwan since 1996. Simulation results indicated that the annual energy savings of VAV system in typical commercial buildings in Taiwan could be up to 70% of total fan power.A full-scale experiment has been performed which validated this result successfully, and would be adapted with the PACS index in the second phase of national Building Energy Code in Taiwan.Copyright

A Comparative Study of Centrifugal Chiller Performances After CFC Refrigerant Conversion

Theoretical analysis indicated that, a typical centrifugal chiller could lose over 8% to 10% of its cooling capacity after converting from R-11 into using R-123 refrigerant. In this study, an attempt to recover some of this capacity loss by slightly decreasing its operating speed was analyzed.A full-scale experiment was performed to change the gear train of a 300 RT centrifugal chillier, which validated that 3%∼6% capacity recovery could be expected. This is a break-through to promote the chiller conversion for wide engineering applications and is discussed in detail in this paper.Copyright