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Heating Capacity (heating + capacity)
Selected AbstractsOptimum selection (design) of thermoelectric modules for large capacity heat pump applicationsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2004S. B. Riffat Abstract Thermoelectric modules should be selected or designed to meet the specific cooling/heating requirements of a particular application and in most cases, the cooling/heating capacity and the working temperatures (hot and cold side temperature of thermoelectric devices) are known. Computer modelling can be used to assist the selection process by determining the relationships between the cooling/heating requirements and optimum thermoelectric parameters thermoelectric modules suited to large capacity thermoelectric heat pump applications. Copyright © 2004 John Wiley & Sons, Ltd. [source] Test method for concrete spalling using small electric furnaceFIRE AND MATERIALS, Issue 4 2010Ren Zhao Abstract Concrete spalling can cause severe damage to concrete structure when exposed to fire. The spalling mechanisms are not very well understood. For the testing of spalling, full-scale structural members should be used, as spalling tests are sensitive to size effects. Full-scale testing in large furnace is costly and is not suitable for testing large number of concrete mixture trials. The standard and hydrocarbon fire time,temperature curves have rapid temperature rise during the initial phase. This temperature rise requires a gas furnace with high heating capacity and cannot be generated by electric muffle furnace commonly available in many laboratories. This paper presents a method to carry out spalling test in small-scale specimens with exposure to rapid temperature rise using a commonly available electric furnace in the laboratories. The tests are based on 150,mm diameter cylinders that are laterally confined to simulate full-scale structural members. The cylinder surface is exposed to rapid temperature rise by exposing through vertical and/or horizontal holes in pre-heated small electric furnace. Some unconfined 100,mm diameter cylinders were also exposed horizontally to test the performance of confinement. The paper shows that the hydrocarbon fire and standard fire exposure can be simulated by manipulating the exposure location of the surface of the concrete cylinder. Ordinary Portland cement concrete cylinders with different strengths were tested and different spalling patterns were observed. The spalling patterns matched the test results from a gas furnace fire test simulating the fire curves. The tests demonstrated that the method is an effective and convenient technique to predict the spalling risk of a concrete. Copyright © 2009 John Wiley & Sons, Ltd. [source] Experimental investigation of the performance of a solar-assisted ground-source heat pump system for greenhouse heatingINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2005Onder Ozgener Abstract The main objective of the present study is to investigate the performance characteristics of a solar-assisted ground-source heat pump system (SAGSHPS) for greenhouse heating with a 50 m vertical 1¼ in nominal diameter U-bend ground heat exchanger. This system was designed and installed in the Solar Energy Institute, Ege University, Izmir (568 degree days cooling, base: 22°C, 1226 degree days heating, base: 18°C), Turkey. Based upon the measurements made in the heating mode, the heat extraction rate from the soil is found to be, on average, 54.08 Wm,1 of bore depth, while the required borehole length in meter per kW of heating capacity is obtained as 12.57. The entering water temperature to the unit ranges from 8.2 to 16.2°C, with an average value of 9.1°C. The greenhouse air is at a maximum day temperature of 25°C and night temperature of 14°C with a relative humidity of 40%. The heating coefficient of performance of the heat pump (COPHP) is about 2.13 at the end of a cloudy day, while it is about 2.84 at the end of sunny day and fluctuates between these values in other times. The COP values for the whole system are also obtained to be 5,15% lower than COPHP. Copyright © 2004 John Wiley & Sons, Ltd. [source] Geothermal energy utilization in TurkeyINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2001G. G. Gunerhan Abstract This paper investigates the status of geothermal development in Turkey as of the end of 1999. Turkey is one of the countries with significant potential in geothermal energy. Resource assessments have been made many times by the Mineral Research and Exploration Directorate (MTA) of Turkey. The main uses of geothermal energy are mostly moderate- and low-temperature applications such as space heating and domestic hot water supply, greenhouse heating, swimming and balneology, industrial processes, heat pumps and electricity generation. The data accumulated since 1962 show that the estimated geothermal power and direct use potential are about 4500 MWe and 31 500 MWt, respectively. The direct use capacity in thermal applications is in total 640 MWt representing only 2 per cent of its total potential. Since 1990, space heating and greenhouse developments have exhibited a significant progress. The total area of greenhouses heated by geothermal energy reached up to about 31 ha with a heating capacity of 69.61 MWt. A geothermal power plant with a capacity of 20.4 MWe and a CO2 factory with a capacity of 40000 ton yr,1 have been operated in the Denizli-Kizildere field since 1984 and 1986, respectively. Ground source heat pumps have been used in residential buildings for heating and cooling for approximately 2 years. Present applications have shown that geothermal energy in Turkey is clean and much cheaper compared to the other energy sources like fossil fuels and therefore is a promising alternative. As the projects are recognized by the public, the progress will continue. Copyright © 2001 John Wiley & Sons, Ltd. [source] Demand side management for water heating installations in South African commercial buildingsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2001P. G. Rousseau Abstract The largest percentage of the sanitary hot water used in South African buildings is heated by means of direct electrical resistance heaters. This is one of the major contributing factors of the undesirable high morning and afternoon peaks imposed on the national electricity supply grid. Water heating therefore continues to be of concern to ESKOM, the country's only electrical utility company. The so-called in-line water heating system design methodology was developed to address this problem. This paper investigates the potential impact of in-line systems on the national peak electrical demand. A computer simulation model was developed that combines a deterministic mathematical model with a statistical approach in order to predict the diversity factors associated with both the existing and in-line design methodologies. A study was also conducted to estimate the total installed water heating capacity in the national commercial building sector. This figure can be combined with the simulated diversity factor to determine the peak electrical demand. The deterministic model includes the detailed simulation of the hot water storage vessel, the electrical heater and the system control algorithm. The mathematical model for the storage vessel is based on an electrical analogue approach that includes the effects of conduction as well as forced and natural convection. This model was verified extensively with the aid of laboratory measurements and compared with existing storage vessel models. It was found that the new storage vessel model could predict the supply temperature within 2 per cent for a system configuration with the heater in parallel outside the reservoir and within 12 per cent for a configuration with the heater situated inside the reservoir. This compares favourably with existing models found in the literature. The complete simulation based on the statistical approach showed that extensive application of the new design methodology could result in a reduction of approximately 75 MW in the total maximum peak demand imposed on the electricity supply grid in wintertime. This is 58 per cent of the current peak demand due to commercial water heating and 12.5 per cent of the peak load reduction target set by ESKOM until the year 2015. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||