[en] We present work on measurement of the energy performance of heat pumps for hotel operations in subtropical climates. Two city hotels in Hong Kong were investigated. The first case was an application of an air-to-water heat pump to provide heating for an outdoor swimming pool during the heating season. The second case was the installation of three water-to-water heat pumps to complement an existing boiler system for hot water supply. The heating energy output and corresponding electricity use were measured. The heat pump energy efficiency was evaluated in terms of the coefficient of performance (COP), defined as the heating energy output to the electrical energy use. The air-to-water heat pump provided 49.1 MW h heating while consuming 24.6 MW h electricity during the 6((1)/(2))-month heating season from mid-October to April. For the water-to-water heat pumps, the estimated annual heating output and the electricity use were 952 and 544 MW h, respectively. It was found that the heat pumps generally operated in a COP range of 1.5-2.4, and the payback period was about two years, which was considered financially attractive

[en] An original methodology for the analysis of systems and processes is developed. The methodology is based on the quantities exergy, cost, energy and mass, and is referred to as EXCEM analysis. The development of a code for EXCEM analysis by enhancing Aspen Plus, a state of the art process simulation code, is described. Applications of the methodology and code to the analysis of several engineering processes (production of electricity, hydrogen and hydrogen derived fuels) are discussed. The relations between exergy loss and capital cost and those between exergy and environmental impact are investigated. EXCEM analysis may prove useful to investigators in engineering and other disciplines

[en] In this study, energy utilization and its major environmental impacts are discussed from the standpoint of sustainable development, including anticipated patterns of future energy use and subsequent environmental issues in Turkey. Several aspects relating to energy utilization, renewable energy, energy efficiency, environment and sustainable development are examined from both current and future perspectives. Turkey is an energy importing country, more than half of the energy requirement has been supplied by imports. Domestic oil and lignite reserves are limited, and the lignites are characterised by high ash, sulfur and moisture content. Because of increasing energy consumption, environmental pollution is becoming a serious problem in the future for the country. In this regard, renewable energy resources appear to be one of the most efficient and effective solutions for sustainable energy development and environmental pollution prevention in Turkey. Turkey's geographical location has several advantages for extensive use of most of these renewable energy sources. Especially hydropower, biomass, geothermal, solar and wind energy should be considered and seriously supported by governments and private sectors

[en] In order to use electricity efficiently, a demand control management system is one of the effective ways to reduce energy consumption and electric bills. An electricity demand control system is used as a means to monitor and manage the usage of electricity effectively. Moreover, it is a useful tool for avoiding penalties beyond the contracted demand value of electricity with the electric power company. In this project, we developed a Taguchi-Grey based predictor to forecast the demand value of electricity on line. In a Grey prediction, the parameter settings are highly relevant to the accuracy of forecasting. A Taguchi method was employed to optimize the parameter settings for the Grey based electricity demand value predictor. Our experimental results show that the optimal parameter settings of the Grey prediction are α=0.4, five point modeling and three minute sampling time of the data acquisition system. The improved Taguchi-Grey based electricity demand predictor in conjunction with the PC based electricity demand control system is a cost effective and efficient means to manage the usage of electricity

[en] Discussions about market introduction of grid connected photovoltaics (PV) and its costs usually concentrate only on the gross energy produced without taking the time dependency of electricity prices and, thus, the time dependency of the value of PV electricity into account. To make a first approximation of what the effect of the time variance of electricity cost on the value of PV electricity is, the correlation with spot market prices is analysed in this paper. PV is not dispatchable by nature, but is relatively well predictable in the range of one day, if the average of spatially dispersed systems is considered. Thus, this correlation gives a good indication for the additional value of PV electricity

[en] In the energy field, an important cause of pollutant emissions is linked to ground transportation. The increase of the ratio between energy consumption due to transport and the gross internal product has been 1.12% per year from 1970. All these energy consumption increases have been made while using fossil fuel with serious environmental consequences on the local and global scale and reduction of fuel availability. Environmental policy points towards improvement by cleaner fuels utilisation and increase of engine efficiencies. In this paper, a specific application will be discussed concerning the public transport service in an Italian urban area: a bus fleet motorised with fuel cell systems will be compared with traditional buses using fossil fuels. The comparison will be done in energy, economic, environmental and social terms

[en] It would be misleading to consider only the construction costs of heat exchangers in their design because high service costs during their service life may also greatly increase total costs. Therefore, energy saving aspects are very important in the design, construction and operation of the heat exchangers. For this reason, various active or passive methods have been sought to save energy by increasing the heat transfer coefficients in the cold and warm fluid sides in the heat exchangers. In this study, the effect of cut out conical turbulators, placed in a heat exchanger tube at constant outer surface temperature, on the heat transfer rates was investigated. The air was passed through the exchanger tube, the outer surface of which was heated with saturated water vapor. The experiments were conducted for air flow rates in the range of 15,000 ≤ Re < 60,000. Heat transfer, pressure loss and exergy analyses were made for the conditions with and without turbulators and compared to each other. Some empirical correlations expressing the results were also derived and discussed

[en] Month-hour equal mean zenith luminance contours are obtained from one year of data of zenith luminance measurements for cloudless, overcast and partly cloudy skies and also when the combined data for all sky types are considered. For many hours in different months, the overcast sky luminance values are roughly about three times the cloudless sky luminance values and one and a half times the partly cloudy sky values. The dependence of month-hour equal mean zenith luminance contours on the ratio of global to extraterrestrial illuminance on a horizontal surface is also given. From equal mean zenith luminance contours, the approximate values of the mean zenith luminance for different sky conditions and different hours and months of the year can be easily obtained. Month-hour equal mean diffuse illuminance contours are obtained from diffuse illuminance measurements performed during the period 1992-1998. The dependence on solar altitude of the monthly average hourly values of diffuse illuminance is given and compared to the corresponding one obtained from data for Bet Dagan (Israel)

[en] This paper describes a study conducted in the lighting sector of office buildings as a part of a broader research study aimed at developing building codes for Sri Lanka addressing lighting as well as thermal comfort in order to optimise the use of electricity within these buildings. The study covered different tasks performed in office buildings and the optimum lighting levels required to perform these tasks in the office environment in Sri Lanka. Also, it included assessing the visual performance of people involved in different activities under varying illumination levels in a controlled environment and a comparison of these optimum lighting levels with international standards. It can be seen that the required optimum lighting levels are generally lower in Sri Lanka in comparison to specified standard levels, and this scenario is likely to be similar in other developing countries too. These findings clearly emphasise the need to adopt lighting standards most appropriate to local conditions, in turn helping improve the energy efficiency within buildings

[en] A method of fault detection, diagnosis (FDD) and data recovery is proposed for building heating/cooling billing system in this paper. Principal component analysis (PCA) approach is used to extract the correlation of measured variables in heating/cooling billing system and reduce the dimension of measured data. The measured data of billing system under normal operating condition are used to build PCA model. Sensor faults of bias, drifting and complete failure are introduced to building heating/cooling billing system for detection and identification. Square prediction error (SPE) statistic is used to detect sensor faults in the system. Then, sensor validity index (SVI) was employed to identify faulty sensors. Finally, a reconstruction algorithm is presented to recover the correct data of faulty sensor in accordance with the correlations among system variables. A program for the FDD and data recovery method is developed and employed in the heating/cooling billing system of a real small-scale laboratory building to test its applicability and effectiveness. Validation results show that the proposed FDD and data recovery method is correct and effective for most faults in building heating/cooling billing system.