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02221 Design optimization of a rolling piston compressor for refrigerators
10 Space heating and cooling~heat pumps The pinch analysis (PA) concept's main drawback is that it is suboptimal since it disregards the chemical reactors network (CRN) contribution to the total flowsheet entropy generation, as it does with the separation trains, if any. The chemical reactors energy integration (CREI) through virtual heat exchangers (VHE) emerged and became, during its crystallization period, an expansion of the classical PA, allowing the CRN to be seen as part of the heat exchangers network (HEN), perhaps leading to a better decrease in the total entropy production both through the inclusion of CRN sources and sinks into the HEN topology, and the improvement of the reactors operating conditions, while preserving their performance, in terms of chemical transformation. Throughout the considered case study, two-bed methanol synthesis heat integrated reactor, the benefits and the drawbacks of the CREI will be emphasized.
06•02217 Constructal multi-scale structures for maximal heat transfer density da Silva, A. K. et al. Energy, 2006, 31, (5), 620 635. This paper reviews recent constructal-theory advances: the optimal distribution of discrete heat sources cooled by laminar natural convection. Three scenarios are investigated: (i) many small heat sources mounted on a vertical wall, (i) a few small finite-size heat sources mounted on the side wall of a two-dimensional enclosure, and (iii) one heated area on the wall of a vertical diverging or converging channel with chimney flow. In (i) and (ii), the optimally distributed heat sources are not equidistant. In (iii), the geometry changes by varying the space between the walls, the distribution of heating along the walls, and the angle between the two walls. Numerical simulations in the Rayleigb number range 105 <_ Rail _< 107 show that for maximal heat transfer rate density it is better to install heated sections at the channel entrance. The optimal angle between the two walls is approximately zero when Ran is large. The robustness of flow architectures with optimized distribution of heat sources is discussed.
06102218 Desalination using spray tower and vapour compression refrigeration system Kumar, S. S. and Mani, A. International Journal of Nuclear Desalination, 2006, 2, (l/, 89-95. A desalination system using a spray tower and vapour compression refrigeration (VCR) system is proposed for obtaining fresh water from brackish water. In the spray tower, simultaneous heat and mass transfer take place between the brackish water and air, which results in the evaporation of the brackish water and humidification of the air. Fresh water is obtained from the humidified air by condensing the water vapour using a VCR system. Parametric studies were carried out to study the effect of various operational parameters on the fresh water production rate.
06•02219
06/02221 Design optimization of a rolling piston compressor for refrigerators Ooi, K. T. Applied Thermal Engineering, 2005, 25, (5-6), 813-829. In this paper, the performance of a rolling piston compressor has been optimized under preset operational conditions and design constraints by employing a multi-variable, direct search, constrained optimization technique. A mathematical model for the compressor was first formulated. The model accounts for geometrical configuration, thermodynamics effects, valve dynamics, flow and mechanical considerations. The accuracy of the model was verified by comparing its prediction with measured results. The model was then linked with an optimization algorithm to search for a combination of some six design dimensions and seven sets of design constraints, for an optimum compressor performance with minimum mechanical losses. The results of the study suggested that for a given compressor swept volume, a proper combination of the compressor design dimensions can lead to significant compressor performance. The theoretical study predicted that a 50% reduction in mechanical loss is possible and this brings about an improvement in the coefficient of performance of the compressor of more than 14%.
06/02222 Economic evaluation of the building envelope and operation period of heating system in terms of thermal comfort Manioglu, G. and Yilmaz, Z. Energy and Buildings', 2006, 38, (3), 266272. One of the most important properties of a passively designed building is to provide thermal comfort conditions for users with a minimum heating energy cost. Therefore, primary parameters affecting heating energy consumption should be determined correctly during the design stage. Building envelope and operation period of the heating system are important parameters affecting total heating energy consumption in the building. In this study, an approach for the determination of the most convenient building envelope-operation period combination in relation to the life cycle cost and climatic comfort is proposed. For the application of the approach, total heat loss and life cycle cost of the building envelope-operation period combinations of a sample building. which is heated intermittently and used during underheated period of the year were calculated and combinations which provide thermal comfort during the occupation period with the minimum life cycle cost are determined as a most convenient combinations. This study is carried out in Istanbul, which is representative city for temperatehumid zone of Turkey.
Desiccant cooling air conditioning: a review
Daou, K. et al. Renewable and Sustainable Energy Reviews, 2006, 10, (2), 55-77. In this paper, the principles underlying the operation of desiccant cooling systems are recalled and their actual technological applications are discussed, Through a literature review, the feasibility of the desiccant cooling in different climates is proven and the advantages it can offer in terms energy and cost savings are underscored. Some commented examples are presented to illustrate how the desiccant cooling can be a perfective supplement to other cooling systems such as traditional vapour compression air conditioning system, the evaporative cooling, and the chilled-ceiling radiant cooling. It is notably shown that the desiccant materials, when associated with evaporative cooling or chilled-ceiling radiant cooling, can render them applicable under a diversity of climatic conditions.
06•02220 Design and performance prediction of a novel zeolite-water adsorption air conditioner Wang, D. C. et al. Energy Conversion and Management, 2006, 47, (5). 590-610. A novel adsorption air conditioner is designed that supplies 8-12~C chilled water for the fan coil in the locomotive operator cabin. Different from other two-bed adsorption cooling systems, this system has two adsorption/desorption chambers. One adsorber, one condenser and one evaporator are housed in one and the same adsorption/ desorption chamber. There are no valves installed in the vacuum side. So, the reliability of the system is improved greatly. This machine uses zeolite and water as the working pairs. This system is driven by 350450°C exhaust gas generated by the internal combustion engine of the locomotive. The designed refrigerating power and coefficient of performance are 5 kW and 0.25, respectively, according to the requirements for the refrigeration output in the locomotive operator cabin and the waste heat provided by the engine. In this paper, a model for this system is described, and the simulation results are discussed. The model is validated in principle by limited experimental data. According to the calculation results, the refrigerating power of the machine is up to 10 kW with gas inlet temperature of 450°C and
340
evaporating temperature of 6.5°C. The adsorber can be heated from 97 to 423°C or cooled from 423 to 97°C in 1320 s. Therefore, the heat and mass transfer performance of the adsorber is improved greatly. A few experimental data prove these conclusions.
Fuel and Energy Abstracts September 2006
06102223 Effect of standing time after usage on the performance of storage-type domestic electrical waterheaters Atikol, U. et al. Journal of the Energy Institute, 2006, 79, (1), 53 58. In many developing countries, storage-type domestic electrical waterheaters (EWHs) are switched 'on' for a few hours just before their use. This makes it difficult to apply utility cyclic control on EWHs, since the water may cool down and there may be a demand for hot water during the shut-down period. An investigation was carried out on a 121 1 EWH in order to study the cooling behaviour and the availability of hot water for different time intervals (referred to as the standing times) between the initial use, defined as a typical shower period, and the consecutive use. It is observed that, as the standing time is increased, the initial temperature gradient in the storage tank decreases and the thermocline is lost completely after 24 h. However, as the second discharging process is started, the temperature gradient is formed again due to incoming cold fluid and its mixing with the hot water at the bottom of the tank. Furthermore, although the temperature of the hot water at the outlet port decreases as the standing time is increased, the volume of water discharged for the temperature to drop 40°C is approximately the same for each standing time. The more the second draw-off is delayed, the smaller the fraction of water discharged at constant temperature, ranging from 40 to 60% of the total storage volume between 0 to 24 h of standing time.
06/02224 Effect of the thermal conductivity of building materials on the steady-state thermal behaviour of underground building envelopes Yuan, Y. et al. Building and Environment, 2006, 41, (3), 330-335. Using a mathematical model of heat transfer of basement, the calculation area is divided into eight rectangles according to the interzone temperature profile estimation (ITPE) technology, and the solution obtained for all the parts by the separation of variables technique. During the solution, the Fourier coefficients are determined by the continuity of the heat flux and boundary conditions, as a result, a system of linear equation group including 14N equations has been
06•02217 Constructal multi-scale structures for maximal heat transfer density da Silva, A. K. et al. Energy, 2006, 31, (5), 620 635. This paper reviews recent constructal-theory advances: the optimal distribution of discrete heat sources cooled by laminar natural convection. Three scenarios are investigated: (i) many small heat sources mounted on a vertical wall, (i) a few small finite-size heat sources mounted on the side wall of a two-dimensional enclosure, and (iii) one heated area on the wall of a vertical diverging or converging channel with chimney flow. In (i) and (ii), the optimally distributed heat sources are not equidistant. In (iii), the geometry changes by varying the space between the walls, the distribution of heating along the walls, and the angle between the two walls. Numerical simulations in the Rayleigb number range 105 <_ Rail _< 107 show that for maximal heat transfer rate density it is better to install heated sections at the channel entrance. The optimal angle between the two walls is approximately zero when Ran is large. The robustness of flow architectures with optimized distribution of heat sources is discussed.
06102218 Desalination using spray tower and vapour compression refrigeration system Kumar, S. S. and Mani, A. International Journal of Nuclear Desalination, 2006, 2, (l/, 89-95. A desalination system using a spray tower and vapour compression refrigeration (VCR) system is proposed for obtaining fresh water from brackish water. In the spray tower, simultaneous heat and mass transfer take place between the brackish water and air, which results in the evaporation of the brackish water and humidification of the air. Fresh water is obtained from the humidified air by condensing the water vapour using a VCR system. Parametric studies were carried out to study the effect of various operational parameters on the fresh water production rate.
06•02219
06/02221 Design optimization of a rolling piston compressor for refrigerators Ooi, K. T. Applied Thermal Engineering, 2005, 25, (5-6), 813-829. In this paper, the performance of a rolling piston compressor has been optimized under preset operational conditions and design constraints by employing a multi-variable, direct search, constrained optimization technique. A mathematical model for the compressor was first formulated. The model accounts for geometrical configuration, thermodynamics effects, valve dynamics, flow and mechanical considerations. The accuracy of the model was verified by comparing its prediction with measured results. The model was then linked with an optimization algorithm to search for a combination of some six design dimensions and seven sets of design constraints, for an optimum compressor performance with minimum mechanical losses. The results of the study suggested that for a given compressor swept volume, a proper combination of the compressor design dimensions can lead to significant compressor performance. The theoretical study predicted that a 50% reduction in mechanical loss is possible and this brings about an improvement in the coefficient of performance of the compressor of more than 14%.
06/02222 Economic evaluation of the building envelope and operation period of heating system in terms of thermal comfort Manioglu, G. and Yilmaz, Z. Energy and Buildings', 2006, 38, (3), 266272. One of the most important properties of a passively designed building is to provide thermal comfort conditions for users with a minimum heating energy cost. Therefore, primary parameters affecting heating energy consumption should be determined correctly during the design stage. Building envelope and operation period of the heating system are important parameters affecting total heating energy consumption in the building. In this study, an approach for the determination of the most convenient building envelope-operation period combination in relation to the life cycle cost and climatic comfort is proposed. For the application of the approach, total heat loss and life cycle cost of the building envelope-operation period combinations of a sample building. which is heated intermittently and used during underheated period of the year were calculated and combinations which provide thermal comfort during the occupation period with the minimum life cycle cost are determined as a most convenient combinations. This study is carried out in Istanbul, which is representative city for temperatehumid zone of Turkey.
Desiccant cooling air conditioning: a review
Daou, K. et al. Renewable and Sustainable Energy Reviews, 2006, 10, (2), 55-77. In this paper, the principles underlying the operation of desiccant cooling systems are recalled and their actual technological applications are discussed, Through a literature review, the feasibility of the desiccant cooling in different climates is proven and the advantages it can offer in terms energy and cost savings are underscored. Some commented examples are presented to illustrate how the desiccant cooling can be a perfective supplement to other cooling systems such as traditional vapour compression air conditioning system, the evaporative cooling, and the chilled-ceiling radiant cooling. It is notably shown that the desiccant materials, when associated with evaporative cooling or chilled-ceiling radiant cooling, can render them applicable under a diversity of climatic conditions.
06•02220 Design and performance prediction of a novel zeolite-water adsorption air conditioner Wang, D. C. et al. Energy Conversion and Management, 2006, 47, (5). 590-610. A novel adsorption air conditioner is designed that supplies 8-12~C chilled water for the fan coil in the locomotive operator cabin. Different from other two-bed adsorption cooling systems, this system has two adsorption/desorption chambers. One adsorber, one condenser and one evaporator are housed in one and the same adsorption/ desorption chamber. There are no valves installed in the vacuum side. So, the reliability of the system is improved greatly. This machine uses zeolite and water as the working pairs. This system is driven by 350450°C exhaust gas generated by the internal combustion engine of the locomotive. The designed refrigerating power and coefficient of performance are 5 kW and 0.25, respectively, according to the requirements for the refrigeration output in the locomotive operator cabin and the waste heat provided by the engine. In this paper, a model for this system is described, and the simulation results are discussed. The model is validated in principle by limited experimental data. According to the calculation results, the refrigerating power of the machine is up to 10 kW with gas inlet temperature of 450°C and
340
evaporating temperature of 6.5°C. The adsorber can be heated from 97 to 423°C or cooled from 423 to 97°C in 1320 s. Therefore, the heat and mass transfer performance of the adsorber is improved greatly. A few experimental data prove these conclusions.
Fuel and Energy Abstracts September 2006
06102223 Effect of standing time after usage on the performance of storage-type domestic electrical waterheaters Atikol, U. et al. Journal of the Energy Institute, 2006, 79, (1), 53 58. In many developing countries, storage-type domestic electrical waterheaters (EWHs) are switched 'on' for a few hours just before their use. This makes it difficult to apply utility cyclic control on EWHs, since the water may cool down and there may be a demand for hot water during the shut-down period. An investigation was carried out on a 121 1 EWH in order to study the cooling behaviour and the availability of hot water for different time intervals (referred to as the standing times) between the initial use, defined as a typical shower period, and the consecutive use. It is observed that, as the standing time is increased, the initial temperature gradient in the storage tank decreases and the thermocline is lost completely after 24 h. However, as the second discharging process is started, the temperature gradient is formed again due to incoming cold fluid and its mixing with the hot water at the bottom of the tank. Furthermore, although the temperature of the hot water at the outlet port decreases as the standing time is increased, the volume of water discharged for the temperature to drop 40°C is approximately the same for each standing time. The more the second draw-off is delayed, the smaller the fraction of water discharged at constant temperature, ranging from 40 to 60% of the total storage volume between 0 to 24 h of standing time.
06/02224 Effect of the thermal conductivity of building materials on the steady-state thermal behaviour of underground building envelopes Yuan, Y. et al. Building and Environment, 2006, 41, (3), 330-335. Using a mathematical model of heat transfer of basement, the calculation area is divided into eight rectangles according to the interzone temperature profile estimation (ITPE) technology, and the solution obtained for all the parts by the separation of variables technique. During the solution, the Fourier coefficients are determined by the continuity of the heat flux and boundary conditions, as a result, a system of linear equation group including 14N equations has been