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The building sector is one major primary energy consumer and pollutant emission source. In recent years, the building-related research studies on the potential use of Maisotsenko-cycle in energy systems have been increasing in recent years. The growing interest lies in its expanded applications beyond the air-conditioning systems (the main “energy consumers” in buildings) into the prime movers (the key players in power generation). In order to evaluate its application merits in the practical tri-generation system of the urban districts, an extensive computer simulation platform has been developed. Based on a case study, this paper describes the techniques in the mixed use of numerical tools in performing system optimization studies for distributed power application on a university campus site. The practicality of the methodology is demonstrated through a hypothetical tri-generation system primed with Maisotsenko combustion turbine cycle. The findings are very much interesting.

The risk of air pollutants like particulate matters on human beings has been widely reported. One main concern is its health impact on people through direct emission or resuspension. In China with the quick growth in private car ownership, the worries about the influence of the moving vehicles on particulate dispersion is growing. In this study, the influence of a moving object on wick formation and particulate dispersion was investigated. An advanced numerical model was developed, in which the unsteady Eulerian RANS model was applied for simulating the airflow, the modified drift-flux model for modelling particulate dispersion, and the dynamic mesh model for mimicking the moving vehicle. The results show that the vehicular movement induces three noticeable vortexes around the moving body, and the faster the running speed, the stronger the secondary airflow generated.

Photovoltaic-thermal (PV/T) systems integrate photovoltaic and solar thermal technologies into one single system with dual production of electricity and heat energy. A typical arrangement is the direct attachment of PV modules onto a solar thermal collector surface. For a given collector surface area, the overall system energy performance is expected higher than the conventional 'side-by-side' PV and solar thermal systems. In the development of PV/T collector technology using water as the coolant, the most common design follows the sheet-and-tube thermal absorber concept. Fin performance of the thermal absorber has been identified as one important factor that affects much the overall energy performance of the collector. Accordingly, an aluminum-alloy flat-box type PV/T collector prototype was constructed and tested in Hong Kong. Our test results indicate that a high combined thermal and electrical efficiency can be achieved. The primary-energy-saving efficiency for daily exposure approaches 65% at zero reduced temperature operation. With a simple and handy design, the product is considered to be very suitable for domestic application. [DOI: 10.1115/1.2711474] Keywords: hybrid solar system, photovoltaic/thermal technology, domestic application

The rapid development and sales volume of photovoltaic (PV) modules has created a promising business environment in the foreseeable future. However, the current electricity cost from PV is still several times higher than from the conventional power generation. One way to shorten the payback period is to bring in the hybrid photovoltaic--thermal (PVT) technology, which multiplies the energy outputs from the same collector surface area. In this paper, the performance evaluation of a new water-type PVT collector system is presented. The thermal collection making use of the thermosyphon principle eliminates the expense of pumping power. Experimental rigs were successfully built. A dynamic simulation model of the PVT collector system was developed and validated by the experimental measurements, together with two other similar models developed for PV module and solar hot-water collector. These were then used to predict the energy outputs and the payback periods for their applications in the subtropical climate, with Hong Kong as an example. The numerical results show that a payback period of 12 year for the PVT collector system is comparable to the side-by-side system, and is much shorter than the plain PV application. This is a great encouragement in marketing the PVT technology. Keywords: Hybrid solar technology; Photovoltaic; Thermosyphon; Dynamic simulation

Abstract A numerical simulation applying a validated computational fluid dynamics model was used to investigate the effect of the headroom on a displacement ventilation (DV) system. Two different headroom heights [...]

Abstract The ventilation system of an operating theatre (OT) in a hospital needs to provide a comfortable and healthy surgical environment, particularly to minimise the risk of airborne infection. Engineering [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.solener.2005.04.017 Byline: T.T. Chow, A.L.S. Chan, K.F. Fong, Z. Lin Keywords: Typical weather year; Building simulation; Climate change Abstract: Accurate prediction of building energy performance requires precise information of the local climate. Typical weather year files like test reference year (TRY) and typical meteorological year (TMY) are commonly used in building simulation. They are also essential for numerical analysis of the sustainable and renewable energy systems. The weather year file of one city is often employed by the nearby cities for such purposes. In this paper, the developments of customized weather year formulation are reviewed. The key issues are discussed making reference to two neighboring cities, Hong Kong and Macau, using their weather data records over a century, and the typical weather year files developed. The findings support the preference of TMY over TRY. It is also suggested that the TMY selection process should include the most recent meteorological observations, and should be periodically reviewed to well reflect the long-term climate change. Author Affiliation: Division of Building Science and Technology, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, SAR, China Article History: Received 20 September 2004; Revised 29 April 2005; Accepted 29 April 2005 Article Note: (miscellaneous) Communicated by: Associate Editor Pierre Ineichen

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.solener.2005.02.003 Byline: T.T. Chow (a), W. He (a), J. Ji (b) Keywords: Hybrid solar collector; Thermosyphon system; Photovoltaic; Residences Abstract: In order to improve the energy performance of the photovoltaic system, much effort has been spent on the research and development of hybrid PVT (photovoltaic-thermal) technology using water as the coolant. The fin performance of the thermal absorber is known to be one crucial factor in achieving a high overall energy yield of the collector. Accordingly, an aluminum-alloy flat-box type PVT collector was constructed, with its fin efficiency approaching unity. Its design is primarily for natural circulation and for domestic water heating purpose. Our test results showed that a high final hot water temperature in the collector system can be achieved after a one-day exposure. A numerical model of this photovoltaic-thermosyphon collector system was also developed and the model accuracy was verified by comparison with measured data. The energy performance of the collector system was then examined first, through reduced-temperature analysis, and second, as applying in the 'hot summer and cold winter' climate zone of China. The numerical results are found very encouraging, and the equipment is capable of extending the PV application potential in the domestic sector. Author Affiliation: (a) Division of Building Science and Technology, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China (b) Department of Thermal Science and Energy Engineering, University of Science and Technology of China, Hefai 230026, Anhui, China Article History: Received 17 November 2004; Revised 26 January 2005; Accepted 7 February 2005 Article Note: (miscellaneous) Communicated by: Associate Editor Mukund Patel

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. [...]

Abstract 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 [...]

Although the performance of hybrid photovoltaic-thermal (PV/T) collector had been studied both experimentally and numerically for some years, the thermal models developed in previous studies were mostly steady-state models for predicting the annual yields. The operation of a PV/T collector is inherently dynamic. A steady-state model is not suitable for predicting working temperatures of the PV module and the heat-removal fluid during periods of fluctuating irradiance or intermittent fluid flow. Based on the control-volume finite-difference approach, an explicit dynamic model was developed for a single-glazed flat-plate water-heating PV/T collector. A transport delay fluid flow model was incorporated. The proposed model is suitable for dynamic system simulation applications. It allows detailed analysis of the transient energy flow across various collector components and captures the instantaneous energy outputs. [c] 2003 Elsevier Ltd. All rights reserved.