Authors:Kasaeian A; Amirifard M, Ahmadi M, et al. Pages: 335 - 348 Abstract: In this study, the influence of ambient temperature is investigated on the performance of solar chimney. Dimensional analysis is performed to find the dimensionless variables for the purpose of predicting the solar chimney performance. A mathematical model was developed and validated with the experimental data of an experimental pilot. By using this model, it is shown that the ambient temperature has an adverse effect on the SCPP output. For this purpose, a solar chimney with 7.4 m chimney height, 0.6 m chimney diameter, 8 m collector diameter, and 0.2 m mean collector height was built. By using the Buckingham Pi theory, a dimensionless variable was obtained, and its value was correlated using the experimental data. The investigation of the system performance using this dimensionless variable shows that the output power increases with a third-order polynomial relation through increasing the size of SCPP, and with a linear relation through increasing the solar insolation. In the other word, when the size of the system and solar insolation increase, the output power of the solar chimney rises. The variation of the air velocity versus daytime shows maximum area from 11:00 a.m. to 1:00 p.m. PubDate: 2017-03-29 DOI: 10.1093/ijlct/ctw016 Issue No:Vol. 12, No. 4 (2017)
Authors:Ghazali A; Salleh E, Chin Haw L, et al. Pages: 349 - 357 Abstract: In order to fully assess the potential of a photovoltaic (PV) application on a building's façade, the amount of energy generated and the cost of the PV installation must be analysed during the design process to enable the designer, investor and end-user to make decisions regarding the implementation of renewable technologies. This paper focuses on the financial evaluation of a vertical PV façade system on a high-rise building in Malaysia, using the System Advisor Model developed by the National Renewable Energy Laboratory of Malaysia, based on five possible design scenarios that all use an amorphous silicon heterojunction module with a nominal efficiency of 15.6%. According to our financial analysis, the payback period for a vertical PV system would be about 12 years, while that of a horizontal system would be 6 years. On average, a PV system on a vertical façade would be able to save 8400–17 000 USD each month compared to a PV roof installation (about 5200 USD each month). This shows that PV installations on vertical façades of high-rise buildings could be implemented in Malaysian climate conditions. With a careful design approach, this could open up a new demographic in the Malaysian built environment and Renewable Energy industries. PubDate: 2017-05-25 DOI: 10.1093/ijlct/ctx002 Issue No:Vol. 12, No. 4 (2017)
Authors:Hegazy I; Seddik W, Ibrahim H. Pages: 358 - 368 Abstract: In developing countries, most cities suffer from numerous problems associated with the processes of their urban management and development. These problems have a great influence on the environmental performance of those cities. Egyptian cities are no exception to such cities. Recently, Egypt has been undergoing rapid urbanization and industrialization. It is claimed that there have been various undesired effects on the environment resulting from these development processes. In fact, it could be said that development processes, as a result of national policy over the past 3 decades, are associated with a wide range of problems and impacts on the environment. In this respect, sustainability has been the most trending issue in developing urban communities all over the world. Great efforts have been made through sustainable urban design to enhance the quality of life. Furthermore, it is advocated that to make these communities sustainable, a comprehensive management of their systems is essential. This research advocates that green mechanisms within urban management in Egypt would offer appropriate solutions for their problems. This research casts light on one of the recent green urban management evaluation mechanisms. The African Green City Index is adopted in this research to examine the environmental performance of three new cities in Egypt, and the commitment made to reducing the environmental impact associated with their urban development. The research concludes with the identification of green policy proposals for improving the selected cities’ environmental performance and urban management. These proposals could be considered as initiatives and guidelines for other Egyptian cities and could pave the way for identifying appropriate policies for enhancing the quality of green city urban systems within the Egyptian context. PubDate: 2017-06-15 DOI: 10.1093/ijlct/ctx009 Issue No:Vol. 12, No. 4 (2017)
Authors:Riffat S; Aydin D, Powell R, et al. Pages: 369 - 382 Abstract: Dependency on energy is much higher than the past and it is clear that energy is vital for a sustainable and safer future. Therefore, urgent solutions are required not only to increase share of renewable resources but also more efficient usage of fossil fuels. This could be achieved with innovative power, air conditioning and refrigeration cycles utilising ‘long-term sustainable’ (LTS) fluids, especially air, water and CO2. In the article we provide a rational approach to the future use of working fluids based on our interpretation of the available technical evidence. We consider it self-evident that volatile fluids will continue to play major roles in cooling and power generation, however, new technologies will be needed that optimise energy efficiency and safety with minimum environmental impact. Concordantly we discuss the past and current situation of volatile fluids and present four innovative technologies using air/water cycles. Study results showed that there is a rapid development in heating, cooling and power generation technologies those use water/air as working fluid. These technologies demonstrate a potential to replace conventional systems, thereby to contribute to global sustainability in near future. However, further development on LTS fluids and materials also process intensification and cost reduction are vital parameters for future advancement of these technologies. PubDate: 2017-06-17 DOI: 10.1093/ijlct/ctx008 Issue No:Vol. 12, No. 4 (2017)
Authors:Sahu A; Agrawal N, Nanda P. Pages: 383 - 391 Abstract: In this work, transcritical CO2 refrigeration cycle and combined refrigeration-power cycle have been studied. Parametric steady state first-law and second-law analysis of the simple refrigeration cycle and combined power-refrigeration cycle have been carried out. The influence of various parameters like evaporator temperature, gas cooler outlet temperature, gas heater pressure and turbine inlet temperature on coefficient of performance (COP) and second-law efficiency has been studied. It has been found that COP and second-law efficiency of combined power cycle is significantly higher as compared to simple cooling-refrigeration cycle under all operating conditions. An optimum pressure for a given gas cooler pressure is also existed for the combined power-refrigeration cycle as like CO2 refrigeration cycle. PubDate: 2017-07-14 DOI: 10.1093/ijlct/ctx006 Issue No:Vol. 12, No. 4 (2017)
Authors:Fang W; Riffat S, Wu Y. Pages: 392 - 399 Abstract: Performance of a microencapsulated phase-change material (PCM) as a heat-transport medium in an evacuated heat pipe solar collector was evaluated and the results compared with those using water. Collector efficiency was experimentally determined according to the method based on European Standard EN 12975–2: 2006. This method proved unsuitable when using an encapsulated PCM suspension. A modified test method was proposed, which was appropriate for predicting solar collector efficiency when using a phase-change fluid. Average solar collection efficiency when using a PCM suspension was higher than that using water. PubDate: 2017-07-31 DOI: 10.1093/ijlct/ctx010 Issue No:Vol. 12, No. 4 (2017)
Authors:Baitule A; Sudhakar K. Pages: 400 - 410 Abstract: Large-scale deployment of the renewable energy system in India is required to achieve a target of 175 GW of green electricity by 2022. Higher educational institutes with a lot of free areas can play a vital role in reducing the conventional energy consumption and carbon footprint. The main aim of this paper is to locate and analyze the feasibility of developing 100% solar PV based academic campus at MANIT – Bhopal, India. Annual electricity consumption of MANIT, Bhopal is analyzed and accordingly 5 MW capacity solar PV based captive plant is proposed. Free open space area of the campus including rooftop area is inspected through geographical coordinates utilizing the NASA surface meteorology data and Google SketchUp. The performance of the proposed solar campus is analyzed using PVSyst and Solar Advisory Model (SAM) software. The proposed plant at MANIT campus can generate around 8000 MWh per annum of electricity to meet the 100% energy requirements of the campus with the annual reduction of 73 318.0 tonnes of carbon footprint. Development and promotion of such sustainable green concepts will be a significant step towards transforming the academic campus into an energy efficient and environmentally sustainable community. PubDate: 2017-08-30 DOI: 10.1093/ijlct/ctx011 Issue No:Vol. 12, No. 4 (2017)
Authors:Ghabra N; Rodrigues L, Oldfield P. Pages: 411 - 419 Abstract: In this paper, the authors explored the hypothesis that the most common approach to improve a building's energy efficiency in the hot climate of Saudi Arabia, which focuses on engineering parameters, is not sufficient and architectural design parameters should be adopted to reduce cooling loads. In order to investigate this hypothesis, 27 sets of dynamic thermal simulations were compared. The best and worst combinations of glazing ratio, wall and glazing type were identified in order to understand the most influential parameter impacting the cooling energy loads in the building. The findings demonstrated that the reliance on a prescriptive approach for building envelope ‘engineering parameters’ specifications does not achieve the required levels of energy efficiency, and the thoughtful consideration of the ‘design parameters’, such as shading elements, could have a significant impact on cooling energy loads. PubDate: 2017-10-11 DOI: 10.1093/ijlct/ctx005 Issue No:Vol. 12, No. 4 (2017)
Authors:Zhang T; Zhu Q, He W, et al. Pages: 420 - 429 Abstract: Based on the typical meteorological year data of Shanghai city, annual performances of solar water heating (SWH) system and photovoltaic/thermal (PV/T) system are comparatively analyzed under three different cases. The results show that when only solar energy is used, the effective day number of SWH system is more than PV/T system under the same case every month; for the PV/T system, heat loss at the nighttime dissipates most of the absorbed solar energy under the continuous heating mode considering the nighttime heat loss case; initial water temperature determines system electric efficiency. On the whole, PV/T system offers competitive performance only under the auxiliary heating mode, no matter from the points of primary efficiency and static payback period. PubDate: 2017-10-23 DOI: 10.1093/ijlct/ctx012 Issue No:Vol. 12, No. 4 (2017)
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