An exhaust heat recovery generator is proposed to be integrated with conventional gas-fired triple-effect LiBr/water absorption cooling cycles to improve system energy efficiency. As a case study, simulation of the no...An exhaust heat recovery generator is proposed to be integrated with conventional gas-fired triple-effect LiBr/water absorption cooling cycles to improve system energy efficiency. As a case study, simulation of the novel cycle based on promising parallel flow with cooling capacity of 1 150 kW is carried out under various heat recovery generator vapor production ratios ranging from 0 to 3.5%. The life cycle saving economic analysis, for which the annual gas conservation is estimated with Bin method, is employed to prove the worthiness of extra expenditure. Results show that the optimum gas saving revenue is obtained at 2.8% heat recovery generator vapor production ratio with 42 kW exhaust heat recovered, and the system energy efficiency is improved from 1.78 to 1.83. The initial investment of exchanger can be paid back within 7 years and 9 000 CNY of gas saving revenue will be achieved over the 15-year life cycle of the machine. This technology can be easily implemented and present desirable economic effects, which is feasible to the development of triple-effect absorption cycles.展开更多
The paper aims to investigate the potential of a water body to influence in lowering the warmth in the city of Sao Jose do Rio Preto, Brazil, due to the evaporative cooling effects. In order to verify its potential, t...The paper aims to investigate the potential of a water body to influence in lowering the warmth in the city of Sao Jose do Rio Preto, Brazil, due to the evaporative cooling effects. In order to verify its potential, three collecting points of temperature and humidity were placed in an urban area close to the municipal dam. The first one was placed on the dam margin, the second one, 50 m distant of the margin and, the third one, 100 m distant. The data were taken during December 2010 and then compared to the climate data of the Climate Station of CIIAGRO-Integrated Center of Agro Meteorological. The results show that the closer the collection point is to the water body, and the lower is the temperature variation. The humidity taxes verified at the closest point to the water body indicate values higher than those ones collected at the most distant point. The insertion of moisture through the water bodies in an urban environment demonstrated to be a strategy that improved the thermal conditions and has to be considered for urban planners to establish strategies of urban occupation.展开更多
Passive strategies for acclimatization of buildings have been studied by several authors in many countries, especially the evaporative and radiant cooling techniques. Fiber cement tiles are very common in popular cons...Passive strategies for acclimatization of buildings have been studied by several authors in many countries, especially the evaporative and radiant cooling techniques. Fiber cement tiles are very common in popular constructions due to their low cost. However, they have over twice of the value thermal transmittance indicated to this bioclimatic zone according to Brazilian guidelines. The objective is to present an alternative to reduce high temperatures on fiber cement tiles. In this paper, the monitoring of passive cooling of roofing during the spring season in a city with subtropical climate is described. Single and combined reflective and evaporative cooling systems were studied in different environmental conditions. Internal surface temperatures of tiles were monitored together with weather variables. Results show a decrease of about 6 ℃, 9 ℃, 10 ℃ and 11 ℃ as compared to the original tiles according to environment conditions and the combined passive cooling techniques. These results allow for the conclusion that the use of passive cooling techniques opens up new possibilities to attenuate the internal surface temperatures of tiles and to consequently decrease the roofing solar heat gain into buildings, thus, providing less air cooling energy consumption.展开更多
Most evaporative cooling towers are arranged on building roof due to the limitation of space and noise,and acoustic barriers are always installed around cooling towers in practical applications.The existence of acoust...Most evaporative cooling towers are arranged on building roof due to the limitation of space and noise,and acoustic barriers are always installed around cooling towers in practical applications.The existence of acoustic barriers and crosswind may affect the recirculation phenomenon which is directly related to the operating performance of cooling towers.In this study,a physical and mathematical computation model is proposed to research the crosswind and distance between acoustic barriers and inlet of cooling towers.Both sensible and latent heat are considered in this research.The reflux flow rate and performance ratio are obtained to evaluate the recirculation and operating performance,respectively.The results show that the higher the crosswind velocity,the larger the reflux flow rate,and the lower the performance ratio of cooling tower groups.For high crosswind velocity,the presence of acoustic barriers is useful to inhibit reflux and improve operating performance,especially for ICE cooling tower groups.In addition,the optimum values are recommended for LiBrllCE cooling tower groups in the research cases The variation of reflux flow rate and performance ratio with the acoustic barriers' distance presents a parabolic tendency.展开更多
基金Supported by National Natural Science Foundation of China (No. 50376044)
文摘An exhaust heat recovery generator is proposed to be integrated with conventional gas-fired triple-effect LiBr/water absorption cooling cycles to improve system energy efficiency. As a case study, simulation of the novel cycle based on promising parallel flow with cooling capacity of 1 150 kW is carried out under various heat recovery generator vapor production ratios ranging from 0 to 3.5%. The life cycle saving economic analysis, for which the annual gas conservation is estimated with Bin method, is employed to prove the worthiness of extra expenditure. Results show that the optimum gas saving revenue is obtained at 2.8% heat recovery generator vapor production ratio with 42 kW exhaust heat recovered, and the system energy efficiency is improved from 1.78 to 1.83. The initial investment of exchanger can be paid back within 7 years and 9 000 CNY of gas saving revenue will be achieved over the 15-year life cycle of the machine. This technology can be easily implemented and present desirable economic effects, which is feasible to the development of triple-effect absorption cycles.
文摘The paper aims to investigate the potential of a water body to influence in lowering the warmth in the city of Sao Jose do Rio Preto, Brazil, due to the evaporative cooling effects. In order to verify its potential, three collecting points of temperature and humidity were placed in an urban area close to the municipal dam. The first one was placed on the dam margin, the second one, 50 m distant of the margin and, the third one, 100 m distant. The data were taken during December 2010 and then compared to the climate data of the Climate Station of CIIAGRO-Integrated Center of Agro Meteorological. The results show that the closer the collection point is to the water body, and the lower is the temperature variation. The humidity taxes verified at the closest point to the water body indicate values higher than those ones collected at the most distant point. The insertion of moisture through the water bodies in an urban environment demonstrated to be a strategy that improved the thermal conditions and has to be considered for urban planners to establish strategies of urban occupation.
文摘Passive strategies for acclimatization of buildings have been studied by several authors in many countries, especially the evaporative and radiant cooling techniques. Fiber cement tiles are very common in popular constructions due to their low cost. However, they have over twice of the value thermal transmittance indicated to this bioclimatic zone according to Brazilian guidelines. The objective is to present an alternative to reduce high temperatures on fiber cement tiles. In this paper, the monitoring of passive cooling of roofing during the spring season in a city with subtropical climate is described. Single and combined reflective and evaporative cooling systems were studied in different environmental conditions. Internal surface temperatures of tiles were monitored together with weather variables. Results show a decrease of about 6 ℃, 9 ℃, 10 ℃ and 11 ℃ as compared to the original tiles according to environment conditions and the combined passive cooling techniques. These results allow for the conclusion that the use of passive cooling techniques opens up new possibilities to attenuate the internal surface temperatures of tiles and to consequently decrease the roofing solar heat gain into buildings, thus, providing less air cooling energy consumption.
文摘Most evaporative cooling towers are arranged on building roof due to the limitation of space and noise,and acoustic barriers are always installed around cooling towers in practical applications.The existence of acoustic barriers and crosswind may affect the recirculation phenomenon which is directly related to the operating performance of cooling towers.In this study,a physical and mathematical computation model is proposed to research the crosswind and distance between acoustic barriers and inlet of cooling towers.Both sensible and latent heat are considered in this research.The reflux flow rate and performance ratio are obtained to evaluate the recirculation and operating performance,respectively.The results show that the higher the crosswind velocity,the larger the reflux flow rate,and the lower the performance ratio of cooling tower groups.For high crosswind velocity,the presence of acoustic barriers is useful to inhibit reflux and improve operating performance,especially for ICE cooling tower groups.In addition,the optimum values are recommended for LiBrllCE cooling tower groups in the research cases The variation of reflux flow rate and performance ratio with the acoustic barriers' distance presents a parabolic tendency.
