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00787 Prediction-based online optimal control of outdoor air of multi-zone VAV air conditioning systems
10 Space heating and cooling/heat pumps 06•00786 Predicting the viscosity of liquid refrigerant blends: comparison with experimental data Royal, D. D. et al. International Journal of Refrigeration, 2005, 28, (3), 311 319. A m e t h o d is p r e s e n t e d for predicting the viscosity of liquid refrigerant mixtures. The m e t h o d has no adjustable p a r a m e t e r s and, in essence, relies upon the k n o w l e d g e of the viscosity of the pure c o m p o n e n t s to predict the viscosity of a mixture by means of kinetic theory and rigidsphere formalism. The predictions have been c o m p a r e d with the available e x p e r i m e n t a l data for a n u m b e r of refrigerant mixtures. Based on this comparison and previous studies, the accuracy of the proposed m e t h o d is assessed to be of the order of ± 7 % .
06•00787 Prediction-based online optimal control of outdoor air of multi-zone VAV air conditioning systems Jin, X. et al. Energy and Buildings, 2005, 37, (9), 939 944. A n o p t i m a l strategy for outdoor air control is developed using a system approach based on prediction to minimize energy consumption. A R M A model is used to predict the energy performance which is expressed by an energy-increment equation. The energy-increment e q u a t i o n is formed to involve the real-time variations of A H U load and energy use of reheaters of V A V terminals. To minimize the Energyi n c r e m e n t equation by genetic algorithm, the optimal settings of outdoor air ratio of A H U and r e h e a t i n g could be obtained. The strategy is tested and evaluated in a simulated e n v i r o n m e n t under various outdoor and indoor conditions.
06•00788 Pumping criterion and dynamic measurements of an inverted U-shape heat driven pump using microchannels and miniature check valves Xu, J. L. and Shi, X. Experimental Thermal andFluid Science, 2005, 29, (5), 579 590. The authors d e m o n s t r a t e d an inverted U-shape heat driven p u m p consisting of a microchannel heat sink, two vertical branches and two m i n i a t u r e check valves. A new criterion, which is governed by the fluid physical properties, the geometry effect and the heat transfer rates at various oscillating stages, was developed. The theory can explain the o p e r a t i n g range of the applied heating power. The dynamic measurements with a high speed data acquisition system shows that periodically a full cycle can be subdivided into a short liquid suction stage, a bulk boiling and a fluid discharge stage, followed by a pressure decrease stage with both of the valves closed. The average mass flow rate is small and can be c o m p u t e d by the energy conservation equation. The cycle period is s h o r t e n e d with increasing the applied heating power. The wall t e m p e r a t u r e s of the microchannel heat sink are oscillating with small a m p l i t u d e s but they are slightly higher than the saturated t e m p e r a t u r e of the working fluid by several degrees. Deionized water was selected as the working fluid. Finally a closed loop heat driven p u m p design incorporating the microchannel heat sink and the condenser fin heat sink is proposed.
06•00789 Sensor-fault detection, diagnosis and estimation for centrifugal chiller systems using principal-component analysis method Wang, S. and Cui, J. Applied Energy, 2005, 82, (3), 197 213. A n online strategy is developed to detect, diagnose and validate sensor faults in centrifugal chillers. Considering thermo-physical characteristics of the water-cooled centrifugal chillers, a dozen sensors of great concern in the chiller-system m o n i t o r i n g and controls were assigned into two models based on p r i n c i p a l - c o m p o n e n t analysis. Each of the two models can group a set of correlated variables and capture the systematic trends of the chillers. The Q-statistic and Q-contribution plot were used to detect and diagnose the sensor faults, respectively. In addition, an a p p r o a c h based on the m i n i m i z a t i o n of squared prediction error of reconstructed vector of variables was used to reconstruct the identified faulty-sensors, i.e. estimate their bias magnitudes. The sensor-fault detection, diagnosis and estimation strategy was validated using an existing building chiller plant while various sensor faults were introduced.
06•00790 Suitable roof constructions for warm climates Gazimagusa case Ozdeniz, M. B. and Hanger, P. Energy and Buildings, 2005, 37, (6), 643 649. This research aims to find the suitable roof constructions for w a r m climates. The research has been carried out at Gazimagusa, North Cyprus. With the limited research b u d g e t 14 different roof constructions were selected and tested on a test house. These constructions included the types that are widely used in Cyprus and also the new ones. The roof constructions were tested under continuously airconditioned and non-acclimatized regimes. They were also tested for the risk of condensation. Most of the research on similar aspects were done in terms of energy loss and gain. This research has been designed to study the roof constructions in terms of t h e r m a l comfort of the users. Naturally, the roof constructions that have the highest t h e r m a l
resistance will result in lowest heat gain and loose. In this study instead of finding the roof constructions that gain the least a m o u n t of heat d u r i n g the hottest days of s u m m e r or the ones which loose the least a m o u n t of heat d u r i n g the coldest days of winter, it was aimed to find how much they provide t h e r m a l comfort t h r o u g h o u t the year. In this respect, the roofs with t h e r m a l insulation showed the best performance. The location of the t h e r m a l insulation materials towards the inner surface of the section increased the performance. Inclined timber roof constructions on reinforced concrete ceiling save the buildings from solar b o m b a r d i n g in summer. However, to prevent the humidity accumulated, the attic space should be very well ventilated. On flat roofs, not only the t h e r m a l resistance of the roof section, but also the light reflectance of outside surface materials affected the t h e r m a l performance. O u t s i d e surface materials with very high light reflectance reduced heat gain in s u m m e r considerably. In buildings that are air conditioned in summer, there is condensation risk. The defects due to this condensation can be avoided by the use of t h e r m a l insulation materials that are not affected from water. There is also condensation risk for winter. However, it was found that this condensation can dry if the building is ventilated.
06•00791 The Lewis factor and its influence on the performance prediction of wet-cooling towers Kloppers, J. G. and KrOger, D. G. hTternational Journal of Thermal Sciences, 2005, 44, (9), 879 884. The effect of the Lewis factor, or Lewis relation, on the performance prediction of natural draft and mechanical draft wet-cooling towers is investigated. The Lewis factor relates the relative rates of heat and mass transfer in wet-cooling towers. The history and d e v e l o p m e n t of the Lewis factor and its application in wet-cooling tower heat and mass transfer analyses are discussed. The relation of the Lewis factor to the Lewis n u m b e r is also investigated. The influence of the Lewis factor on the prediction of wet-cooling tower performance is subsequently investigated. The Poppe heat and mass transfer analysis of evaporative cooling are considered as the Lewis factor can be explicitly specified. It is found that if the same definition or value of the Lewis factor is employed in the fill test analysis and in the s u b s e q u e n t cooling tower performance analysis, the w a t e r outlet t e m p e r a t u r e will be accurately predicted. The a m o u n t of water that evaporates, however, is a function of the actual value of the Lewis factor. If the inlet a m b i e n t air t e m p e r a t u r e is relatively high, the influence of the Lewis factor, on tower performance diminishes. It is very important, in the view of the Lewis factor that any cooling tower fill test be conducted under conditions that are as close as possible to the conditions specified for cooling tower operating conditions.
06/00792 Thermal building behaviour in summer: long-term data evaluation using simplified models Pfafferott, J. et al. Energy and Buildings, 2005, 37, (8), 844 852. This study focuses on the impact of the meteorological e n v i r o n m e n t and the building's t h e r m a l inertia on the indoor t e m p e r a t u r e performance in a passively cooled office building with night ventilation. D a t a from a long-term m o n i t o r i n g campaign and short-term measurements are used to identify the correlation between outdoor and indoor t e m p e r a t u r e in a building under ordinary use and to derive the energy balance of an office room. T e m p e r a t u r e performance and energy balance are m e r g e d in a comprehensive t h e r m o d y n a m i c model, which takes steady-state conditions, short-term and long-term dynamics into account. In contrast to extensive simulation studies, the p r e s e n t e d m e t h o d is based on a straightforward m a t h e m a t i c a l model using Fourier analysis of t e m p e r a t u r e time series and an energy balance model, which focuses on f u n d a m e n t a l information.
06/00793 Thermal environment in Swedish hospitals, Summer and winter measurements Skoog, J. et al. Energy and Buildings, 2005, 37, (8), 872 877. Two distinct groups of individuals (staff and patients) occupy hospital environments. The physical, social and individual needs of the patients as well as of the nursing staff vary to a large extent. Consequently, it is i m p o r t a n t to provide for a comfortable indoor e n v i r o n m e n t for both groups of individuals. The variations between the groups m a k e it hard to optimize the indoor e n v i r o n m e n t for all individuals. Objective m e a s u r e m e n t s and distribution of questionnaires were a d m i n i s t r a t e d in an o r t h o p a e d i c ward. Questionnaires were distributed in order to learn more about how the indoor e n v i r o n m e n t is perceived. To assess the response to the questionnaires, physical indoor climate variables were m e a s u r e d simultaneously. A combination of objective m e a s u r e m e n t s and questionnaires is a suitable m e t h o d to assess and analyse the indoor e n v i r o n m e n t in hospital buildings. The data was collected during s u m m e r and winter to in order to identify possible seasonal variations. C o m p a r i s o n s show that the difference between staff and patients perception of the indoor air t e m p e r a t u r e differ more during winter than s u m m e r despite that physical m e a s u r e m e n t s showed that the t e m p e r a t u r e s were similar in both seasons.
Fuel and Energy Abstracts
March 2006
117
06•00787 Prediction-based online optimal control of outdoor air of multi-zone VAV air conditioning systems Jin, X. et al. Energy and Buildings, 2005, 37, (9), 939 944. A n o p t i m a l strategy for outdoor air control is developed using a system approach based on prediction to minimize energy consumption. A R M A model is used to predict the energy performance which is expressed by an energy-increment equation. The energy-increment e q u a t i o n is formed to involve the real-time variations of A H U load and energy use of reheaters of V A V terminals. To minimize the Energyi n c r e m e n t equation by genetic algorithm, the optimal settings of outdoor air ratio of A H U and r e h e a t i n g could be obtained. The strategy is tested and evaluated in a simulated e n v i r o n m e n t under various outdoor and indoor conditions.
06•00788 Pumping criterion and dynamic measurements of an inverted U-shape heat driven pump using microchannels and miniature check valves Xu, J. L. and Shi, X. Experimental Thermal andFluid Science, 2005, 29, (5), 579 590. The authors d e m o n s t r a t e d an inverted U-shape heat driven p u m p consisting of a microchannel heat sink, two vertical branches and two m i n i a t u r e check valves. A new criterion, which is governed by the fluid physical properties, the geometry effect and the heat transfer rates at various oscillating stages, was developed. The theory can explain the o p e r a t i n g range of the applied heating power. The dynamic measurements with a high speed data acquisition system shows that periodically a full cycle can be subdivided into a short liquid suction stage, a bulk boiling and a fluid discharge stage, followed by a pressure decrease stage with both of the valves closed. The average mass flow rate is small and can be c o m p u t e d by the energy conservation equation. The cycle period is s h o r t e n e d with increasing the applied heating power. The wall t e m p e r a t u r e s of the microchannel heat sink are oscillating with small a m p l i t u d e s but they are slightly higher than the saturated t e m p e r a t u r e of the working fluid by several degrees. Deionized water was selected as the working fluid. Finally a closed loop heat driven p u m p design incorporating the microchannel heat sink and the condenser fin heat sink is proposed.
06•00789 Sensor-fault detection, diagnosis and estimation for centrifugal chiller systems using principal-component analysis method Wang, S. and Cui, J. Applied Energy, 2005, 82, (3), 197 213. A n online strategy is developed to detect, diagnose and validate sensor faults in centrifugal chillers. Considering thermo-physical characteristics of the water-cooled centrifugal chillers, a dozen sensors of great concern in the chiller-system m o n i t o r i n g and controls were assigned into two models based on p r i n c i p a l - c o m p o n e n t analysis. Each of the two models can group a set of correlated variables and capture the systematic trends of the chillers. The Q-statistic and Q-contribution plot were used to detect and diagnose the sensor faults, respectively. In addition, an a p p r o a c h based on the m i n i m i z a t i o n of squared prediction error of reconstructed vector of variables was used to reconstruct the identified faulty-sensors, i.e. estimate their bias magnitudes. The sensor-fault detection, diagnosis and estimation strategy was validated using an existing building chiller plant while various sensor faults were introduced.
06•00790 Suitable roof constructions for warm climates Gazimagusa case Ozdeniz, M. B. and Hanger, P. Energy and Buildings, 2005, 37, (6), 643 649. This research aims to find the suitable roof constructions for w a r m climates. The research has been carried out at Gazimagusa, North Cyprus. With the limited research b u d g e t 14 different roof constructions were selected and tested on a test house. These constructions included the types that are widely used in Cyprus and also the new ones. The roof constructions were tested under continuously airconditioned and non-acclimatized regimes. They were also tested for the risk of condensation. Most of the research on similar aspects were done in terms of energy loss and gain. This research has been designed to study the roof constructions in terms of t h e r m a l comfort of the users. Naturally, the roof constructions that have the highest t h e r m a l
resistance will result in lowest heat gain and loose. In this study instead of finding the roof constructions that gain the least a m o u n t of heat d u r i n g the hottest days of s u m m e r or the ones which loose the least a m o u n t of heat d u r i n g the coldest days of winter, it was aimed to find how much they provide t h e r m a l comfort t h r o u g h o u t the year. In this respect, the roofs with t h e r m a l insulation showed the best performance. The location of the t h e r m a l insulation materials towards the inner surface of the section increased the performance. Inclined timber roof constructions on reinforced concrete ceiling save the buildings from solar b o m b a r d i n g in summer. However, to prevent the humidity accumulated, the attic space should be very well ventilated. On flat roofs, not only the t h e r m a l resistance of the roof section, but also the light reflectance of outside surface materials affected the t h e r m a l performance. O u t s i d e surface materials with very high light reflectance reduced heat gain in s u m m e r considerably. In buildings that are air conditioned in summer, there is condensation risk. The defects due to this condensation can be avoided by the use of t h e r m a l insulation materials that are not affected from water. There is also condensation risk for winter. However, it was found that this condensation can dry if the building is ventilated.
06•00791 The Lewis factor and its influence on the performance prediction of wet-cooling towers Kloppers, J. G. and KrOger, D. G. hTternational Journal of Thermal Sciences, 2005, 44, (9), 879 884. The effect of the Lewis factor, or Lewis relation, on the performance prediction of natural draft and mechanical draft wet-cooling towers is investigated. The Lewis factor relates the relative rates of heat and mass transfer in wet-cooling towers. The history and d e v e l o p m e n t of the Lewis factor and its application in wet-cooling tower heat and mass transfer analyses are discussed. The relation of the Lewis factor to the Lewis n u m b e r is also investigated. The influence of the Lewis factor on the prediction of wet-cooling tower performance is subsequently investigated. The Poppe heat and mass transfer analysis of evaporative cooling are considered as the Lewis factor can be explicitly specified. It is found that if the same definition or value of the Lewis factor is employed in the fill test analysis and in the s u b s e q u e n t cooling tower performance analysis, the w a t e r outlet t e m p e r a t u r e will be accurately predicted. The a m o u n t of water that evaporates, however, is a function of the actual value of the Lewis factor. If the inlet a m b i e n t air t e m p e r a t u r e is relatively high, the influence of the Lewis factor, on tower performance diminishes. It is very important, in the view of the Lewis factor that any cooling tower fill test be conducted under conditions that are as close as possible to the conditions specified for cooling tower operating conditions.
06/00792 Thermal building behaviour in summer: long-term data evaluation using simplified models Pfafferott, J. et al. Energy and Buildings, 2005, 37, (8), 844 852. This study focuses on the impact of the meteorological e n v i r o n m e n t and the building's t h e r m a l inertia on the indoor t e m p e r a t u r e performance in a passively cooled office building with night ventilation. D a t a from a long-term m o n i t o r i n g campaign and short-term measurements are used to identify the correlation between outdoor and indoor t e m p e r a t u r e in a building under ordinary use and to derive the energy balance of an office room. T e m p e r a t u r e performance and energy balance are m e r g e d in a comprehensive t h e r m o d y n a m i c model, which takes steady-state conditions, short-term and long-term dynamics into account. In contrast to extensive simulation studies, the p r e s e n t e d m e t h o d is based on a straightforward m a t h e m a t i c a l model using Fourier analysis of t e m p e r a t u r e time series and an energy balance model, which focuses on f u n d a m e n t a l information.
06/00793 Thermal environment in Swedish hospitals, Summer and winter measurements Skoog, J. et al. Energy and Buildings, 2005, 37, (8), 872 877. Two distinct groups of individuals (staff and patients) occupy hospital environments. The physical, social and individual needs of the patients as well as of the nursing staff vary to a large extent. Consequently, it is i m p o r t a n t to provide for a comfortable indoor e n v i r o n m e n t for both groups of individuals. The variations between the groups m a k e it hard to optimize the indoor e n v i r o n m e n t for all individuals. Objective m e a s u r e m e n t s and distribution of questionnaires were a d m i n i s t r a t e d in an o r t h o p a e d i c ward. Questionnaires were distributed in order to learn more about how the indoor e n v i r o n m e n t is perceived. To assess the response to the questionnaires, physical indoor climate variables were m e a s u r e d simultaneously. A combination of objective m e a s u r e m e n t s and questionnaires is a suitable m e t h o d to assess and analyse the indoor e n v i r o n m e n t in hospital buildings. The data was collected during s u m m e r and winter to in order to identify possible seasonal variations. C o m p a r i s o n s show that the difference between staff and patients perception of the indoor air t e m p e r a t u r e differ more during winter than s u m m e r despite that physical m e a s u r e m e n t s showed that the t e m p e r a t u r e s were similar in both seasons.
Fuel and Energy Abstracts
March 2006
117