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02215 Boiling heat-transfer coefficient variation for R407C inside horizontal tubes of a refrigerating vapour-compression plant's shell-and-tube evaporator
10 Space heating and cooling~heat pumps bubbling fluidized bed combustor are presented. Shrinkage of single fuel particles was measured in the longitudinal and transverse directions (with respect to the wood fibre) for various fuel particle shapes-like disc (l/d= 0.2 0.67), cylinder (l/d~l) and rod (l/d= 2-10). The fuel particle dimensions ranged from 5 to 100 mm. The effect of the bed temperature on the shrinkage was studied by varying the bed temperature in the range of 650 850°C. Fuel particle shape and size were found to influence the shrinkage in the two mutually perpendicular directions. The variation in the fuel particle heating rates for various shapes and sizes was found to be the cause of the variation i~ the shrinkage values. For all the shapes and sizes considered, the longitudinal shrinkage was found to be in the range of 6.5-24%, the transverse shrinkage from 14% to 29%, and the volumetric shrinkage from 35% to 58%. The average volumetric shrinkage was estimated to be 47% with a standard deviation of ±3.8%. Shrinkage increased negligibly with the increase in bed temperature. Increase in fuel particle density led to a decrease in volumetric shrinkage, however, this effect was not conclusive because of the effect of other factors-like chemical composition and wood type. Correlations for estimating the shrinkage coefficients in the two principal directions are presented.
06•02209 Synthesis of industrial utility systems: costeffective de-carbonisation Varbanov, P. et al. Applied Thermal Engineering, 2005, 25, (7), 985 1001. The production processes on industrial sites require large amounts of heating, cooling and power for their operation. Therefore, the optimal synthesis of utility systems is of central interest to engineers in the process industries. Recently, the problem of the global climate change has brought forward the question of reducing significantly the emissions of greenhouse gases into the atmosphere. In this paper, a new approach is presented for cost-effective de-carbonization of new utility systems in the process industries. This is based on improved models of utility equipment components and an improved model and procedure for optimal synthesis of utility systems.
10
SPACE HEATING A N D COOLING/HEAT PUMPS
06•02210 A long term study of residential home heating consumption and the effect of occupant behavior on homes in the Pacific northwest constructed according to improved thermal standards Emery, A. F. and Kippenhan, C. J. Energy, 2006, 31, (5), 677 693. The space heating energy needed during the winter heating season in Seattle, Washington, USA, was monitored over a 15-year period, 19872002. Two single-family residence houses were constructed to building code standards in force at the time of construction and two to standards calling for envelopes with improved thermal resistance. Space conditioning energy needs are strongly affected by occupant behaviour, but generally simulations ignore the behaviour of the occupants in estimating the energy needed for heating and cooling. The data suggest that estimates of energy savings can be based upon envelope thermal resistance for moderate occupant behaviour. For such behaviour, the space heating is well characterized by the daily average difference between house average space temperature and outside air temperature. Characterizing in terms of indoor temperature, outdoor air temperature, wind speed, and insolation gives a slightly better representation but requires more information than is usually available. However, vigorous conservation tactics, which produce a thermal response that is highly transient, can lead to substantially different energy needs. No correlation could be established from the measured space heating when aggressive conservation made use of thermostat setback at every opportunity.
06/02211 A method for the experimental evaluation in situ of the wall conductance Cucumo, M. et al. Energy and Buildings, 2006, 38, (3), 238-244. A method for the experimental determination of the bt situ building's wall conductance is presented, based on the measurement of wall inside heat flux and inside and outside surface temperatures and on the use of a finite differences calculation code. By applying the method to a test wall, in different periods of time, the conductance values proved to be in agreement with values obtained by the mean progressive method suggested by the EN 12494 pre-regulation. This method has limits in its use since the thermal energy accumulated in the wall has to be negligible compared to the thermal energy passing through the wall during the testing period, whereas the method proposed by the authors can be used more generally and also allows the value of equivalent thermal capacity to be obtained.
06102212 A new design approach for shell-and-tube heat exchangers using genetic algorithms from economic point of view Selbas, R. et al. Chemical Engineering and Processing, 2006, 45, (4), 268 275. A heat exchanger is a device that is used to transfer heat between two or more fluids that are at different temperatures. Heat exchangers are essential elements in a wide range of systems, including the human body, automobiles, computers, power plants, and comfort heating/ cooling equipment. The most commonly used type of heat exchanger is the shell-and-tube heat exchanger, the optimal design of which is the main objective of this study. A primary objective in the heat exchanger design is the estimation of the minimum heat transfer area required for a given heat duty, as it governs the overall cost of the heat exchanger. However there is no concrete objective function that can be expressed explicitly as a function of design variables and in fact many numbers of discrete combinations of the design variables are possible. In the present study, genetic algorithms (GA) has been successfully applied for the optimal design of shell-and-tube heat exchanger by varying the design variables: outer tube diameter, tube layout, number of tube passes, outer shell diameter, baffle spacing and baffle cut. LMTD method is used to determine the heat transfer area for a given design configuration.
06•02213 systems
Air leakage measurement and analysis in duct
Aydin, C. and Ozerdem, B. Energy and Buildings, 2006, 38, (3), 207 213. Air ducts and related equipments are used in a large number of buildings having thermal comfort. In this study, energy loss related with air leakage is studied. The leakage measurement setup was produced according to NEN-EN standards and the evaluation of data have been conducted by using power law model. The measurements were made on 300 and 1000 mm diameter single circular ducts, 300 mm x 250 mm and 1000 m m x 500 mm flanged joint rectangular ducts, 300 and 630 mm diameter circular beaded slip joint ducts, 300 mm x 200 mm and 500 mm x 300 mm rectangular flanged and drive slip joint ducts, and an branched air distribution system having different diameters for positive internal pressures. Test results have showed that the most of air leakage is from the joints. The seam contribution to air leakage is relatively lower than the joints. Using sealing gaskets help to improve the air leakage by about 50%.
06/02214 Application of computational fluid dynamics and pedestrian-behavior simulations to the design of taskambient air-conditioning systems of a subway station Fukuyo, K. Energy, 2006, 31, (5), 706 718. The effects of task-ambient (TA) air-conditioning systems on the airconditioning loads in a subway station and the thermal comfort of passengers were studied using computational fluid dynamics (CFD) and pedestrian-behaviour simulations. The pedestrian-behaviour model was applied to a standard subway station. Task areas were set up to match with crowdedness as predicted by the pedestrian-behaviour simulations. Subsequently, a variety of TA air-conditioning systems were designed to selectively control the microclimate of the task areas. Their effects on the thermal environment in the station in winter were predicted by CFD. The results were compared with those of a conventional air-conditioning system and evaluated in relation to the thermal comfort of subway users and the air-conditioning loads. The comparison showed that TA air-conditioning systems improved thermal comfort and decreased air-conditioning loads.
06•02215 Boiling heat-transfer coefficient variation for R407C inside horizontal tubes of a refrigerating vapourcompression plant's shell-and-tube evaporator Torrella, E. et al. Applied Energy, 2006, 83, (3), 239 252. This paper presents experimental results obtained from a refrigerating vapour-compression plant's shell-and-tube evaporator working with R407C. Several tests have been carried out to study the influence of the evaporating pressure and the refrigerant's mass flow rate on the refrigerant's boiling heat-transfer coefficient inside horizontal tubes. This work has been performed by analysing the variations of the evaporator's overall thermal-resistance, computed using the effectiveness-NTU method, considering the influence of pressure drops and glide at the evaporator, and finally transferring the results and conclusions to the boiling heat-transfer coefficient. It has been observed that the variations of the boiling heat-transfer coefficient show a dependence on the evaporating temperature and the refrigerant's mass-flow rate, which has been analysed in the test range.
06/02216 Chemical reactors energy integration through virtual heat exchangers - benefits and drawbacks Lavric, V. et al. Applied Thermal Engineering, 2005, 25, (7), 1033-1044. Fuel and Energy Abstracts
September 2006
339
06•02209 Synthesis of industrial utility systems: costeffective de-carbonisation Varbanov, P. et al. Applied Thermal Engineering, 2005, 25, (7), 985 1001. The production processes on industrial sites require large amounts of heating, cooling and power for their operation. Therefore, the optimal synthesis of utility systems is of central interest to engineers in the process industries. Recently, the problem of the global climate change has brought forward the question of reducing significantly the emissions of greenhouse gases into the atmosphere. In this paper, a new approach is presented for cost-effective de-carbonization of new utility systems in the process industries. This is based on improved models of utility equipment components and an improved model and procedure for optimal synthesis of utility systems.
10
SPACE HEATING A N D COOLING/HEAT PUMPS
06•02210 A long term study of residential home heating consumption and the effect of occupant behavior on homes in the Pacific northwest constructed according to improved thermal standards Emery, A. F. and Kippenhan, C. J. Energy, 2006, 31, (5), 677 693. The space heating energy needed during the winter heating season in Seattle, Washington, USA, was monitored over a 15-year period, 19872002. Two single-family residence houses were constructed to building code standards in force at the time of construction and two to standards calling for envelopes with improved thermal resistance. Space conditioning energy needs are strongly affected by occupant behaviour, but generally simulations ignore the behaviour of the occupants in estimating the energy needed for heating and cooling. The data suggest that estimates of energy savings can be based upon envelope thermal resistance for moderate occupant behaviour. For such behaviour, the space heating is well characterized by the daily average difference between house average space temperature and outside air temperature. Characterizing in terms of indoor temperature, outdoor air temperature, wind speed, and insolation gives a slightly better representation but requires more information than is usually available. However, vigorous conservation tactics, which produce a thermal response that is highly transient, can lead to substantially different energy needs. No correlation could be established from the measured space heating when aggressive conservation made use of thermostat setback at every opportunity.
06/02211 A method for the experimental evaluation in situ of the wall conductance Cucumo, M. et al. Energy and Buildings, 2006, 38, (3), 238-244. A method for the experimental determination of the bt situ building's wall conductance is presented, based on the measurement of wall inside heat flux and inside and outside surface temperatures and on the use of a finite differences calculation code. By applying the method to a test wall, in different periods of time, the conductance values proved to be in agreement with values obtained by the mean progressive method suggested by the EN 12494 pre-regulation. This method has limits in its use since the thermal energy accumulated in the wall has to be negligible compared to the thermal energy passing through the wall during the testing period, whereas the method proposed by the authors can be used more generally and also allows the value of equivalent thermal capacity to be obtained.
06102212 A new design approach for shell-and-tube heat exchangers using genetic algorithms from economic point of view Selbas, R. et al. Chemical Engineering and Processing, 2006, 45, (4), 268 275. A heat exchanger is a device that is used to transfer heat between two or more fluids that are at different temperatures. Heat exchangers are essential elements in a wide range of systems, including the human body, automobiles, computers, power plants, and comfort heating/ cooling equipment. The most commonly used type of heat exchanger is the shell-and-tube heat exchanger, the optimal design of which is the main objective of this study. A primary objective in the heat exchanger design is the estimation of the minimum heat transfer area required for a given heat duty, as it governs the overall cost of the heat exchanger. However there is no concrete objective function that can be expressed explicitly as a function of design variables and in fact many numbers of discrete combinations of the design variables are possible. In the present study, genetic algorithms (GA) has been successfully applied for the optimal design of shell-and-tube heat exchanger by varying the design variables: outer tube diameter, tube layout, number of tube passes, outer shell diameter, baffle spacing and baffle cut. LMTD method is used to determine the heat transfer area for a given design configuration.
06•02213 systems
Air leakage measurement and analysis in duct
Aydin, C. and Ozerdem, B. Energy and Buildings, 2006, 38, (3), 207 213. Air ducts and related equipments are used in a large number of buildings having thermal comfort. In this study, energy loss related with air leakage is studied. The leakage measurement setup was produced according to NEN-EN standards and the evaluation of data have been conducted by using power law model. The measurements were made on 300 and 1000 mm diameter single circular ducts, 300 mm x 250 mm and 1000 m m x 500 mm flanged joint rectangular ducts, 300 and 630 mm diameter circular beaded slip joint ducts, 300 mm x 200 mm and 500 mm x 300 mm rectangular flanged and drive slip joint ducts, and an branched air distribution system having different diameters for positive internal pressures. Test results have showed that the most of air leakage is from the joints. The seam contribution to air leakage is relatively lower than the joints. Using sealing gaskets help to improve the air leakage by about 50%.
06/02214 Application of computational fluid dynamics and pedestrian-behavior simulations to the design of taskambient air-conditioning systems of a subway station Fukuyo, K. Energy, 2006, 31, (5), 706 718. The effects of task-ambient (TA) air-conditioning systems on the airconditioning loads in a subway station and the thermal comfort of passengers were studied using computational fluid dynamics (CFD) and pedestrian-behaviour simulations. The pedestrian-behaviour model was applied to a standard subway station. Task areas were set up to match with crowdedness as predicted by the pedestrian-behaviour simulations. Subsequently, a variety of TA air-conditioning systems were designed to selectively control the microclimate of the task areas. Their effects on the thermal environment in the station in winter were predicted by CFD. The results were compared with those of a conventional air-conditioning system and evaluated in relation to the thermal comfort of subway users and the air-conditioning loads. The comparison showed that TA air-conditioning systems improved thermal comfort and decreased air-conditioning loads.
06•02215 Boiling heat-transfer coefficient variation for R407C inside horizontal tubes of a refrigerating vapourcompression plant's shell-and-tube evaporator Torrella, E. et al. Applied Energy, 2006, 83, (3), 239 252. This paper presents experimental results obtained from a refrigerating vapour-compression plant's shell-and-tube evaporator working with R407C. Several tests have been carried out to study the influence of the evaporating pressure and the refrigerant's mass flow rate on the refrigerant's boiling heat-transfer coefficient inside horizontal tubes. This work has been performed by analysing the variations of the evaporator's overall thermal-resistance, computed using the effectiveness-NTU method, considering the influence of pressure drops and glide at the evaporator, and finally transferring the results and conclusions to the boiling heat-transfer coefficient. It has been observed that the variations of the boiling heat-transfer coefficient show a dependence on the evaporating temperature and the refrigerant's mass-flow rate, which has been analysed in the test range.
06/02216 Chemical reactors energy integration through virtual heat exchangers - benefits and drawbacks Lavric, V. et al. Applied Thermal Engineering, 2005, 25, (7), 1033-1044. Fuel and Energy Abstracts
September 2006
339