L.S. Chan

A Comparative Study of PV Glazing Performance in Warm Climate

In this experimental study, the performance of ventilated double-pane glazing integrated with semi-transparent solar cells under the subtropical climate of Hong Kong has been investigated. The effects of a photovoltaic (PV) ventilated glazing system on the built environment — including heat and light transmission, thermal and visual comfort, and electricity generation — were analyzed and discussed. While the energy saving potential of PV glazing on air-conditioning demands was found promising, the same on daylight utilization was much inferior to the absorptive glazing applications. The purpose of the study was to gain experience on better use of the semi-transparent PV ventilated glazing technology, and on the energy/cost saving potential of some innovative arrangements.

Effect of Air Supply Temperature on the Performance of Displacement Ventilation (Part I) - Thermal Comfort

The effect of the air supply temperature on the performance of a displacement ventilation (DV) system has been investigated. The study looks into the case of a typical office building in Hong Kong, under local thermal environment and airflow conditions. These are characterised by the high cooling load density, which commonly occurs in Hong Kong. The lower supply temperatures were found to result in higher draft effects, yet increasing temperatures leads to an increase in the predicted percentage of dissatisfied people (PPD). The DV system was found to provide acceptable thermal comfort at certain air supply temperatures. The levels of PPD could be marginal should the parameters of the system not be optimised.

Validation of CFD Model for Research into Displacement Ventilation

The use of turbulence models leads to uncertainties in the computed results because the models are not universal. Therefore, it is essential to validate the CFD program by experimental data. A computational fluid dynamics (CFD) program with the Re-Normalization Group (RNG) k-ϵ model was used for prediction. Validation was conducted by comparing the flow patterns, vertical profiles of temperature, concentration, velocity, and turbulence intensity between measurement and computation for an individual office, a cubicle office, and a quarter of a classroom. The computed air temperature and velocity agree well with the measured data. The agreement is less satisfactory between the computed and measured temperatures in the lower part of the office. The CFD model used therefore should be able to predict the indoor environments characterized by strong pressure and buoyancy driven flows.

Stratum Ventilation for a Workshop under Elevated Indoor Temperature

Abstract The performance of stratum ventilation, a recently developed ventilation strategy, is assessed in terms of thermal comfort and indoor air quality using experimental and computational fluid dynamics (CFD) techniques. The case of a typical Hong Kong workshop under local thermal boundary conditions is used to examine the ventilation system. Various factors including percentage dissatisfied (PD) and mean air age/CO2 were computed to determine the system performance. The stratum ventilation is shown to produce improved indoor air quality and thermal comfort for this particular case study.

Experimental study of evacuated-tube solar water heaters in Hong Kong

The evacuated tube solar water heaters are widely in use today. But so far their thermal performance has not been systematically evaluated, despite the increased popularity. An experimental solar hot water system including two collector types, namely water-in-glass and heat-pipe, of evacuated tube solar water heater has been set up. Their capacity is typical for serving single family domestic hot water system. Performance tests were carried out in Hong Kong and under almost identical boundary conditions by placing the two collectors side-by-side. The energy performance has been analysed and the daily efficiency, transient efficiency and night-time heat loss were compared. While the energy acquisition performance of the heat-pipe collector design is found slightly better, the heat loss performance is found weaker than the water-in-glass collector design.