In conventional absorption refrigeration systems(ARS),the heat from the condenser is usually rejected by the environment in place to be used in the system,so recuperating this is a good alternative to enhance the sys...In conventional absorption refrigeration systems(ARS),the heat from the condenser is usually rejected by the environment in place to be used in the system,so recuperating this is a good alternative to enhance the system’s performance.For instance,in this paper,an alternative ARS in which LiBr/Water is used as a refrigerant mixture,where part of condensing heat is recovered via the solution heat recovery generator absorption cycle(HR-ARS)was energy and exergy evaluated.The influence of generator,condenser and evaporator temperatures,as well as the efficiency of the solution heat exchanger on the coefficient of performance,exergy performance and exergy destroyed of the HR-ARS system,were analyzed and compared with the traditional ARS system at the same working conditions.The results showed an increase between 5.8%–6.3%on the COP and 3.7%–9.5%in the exergy efficiency when condenser/absorber temperature was reduced from 40℃ to 30℃.However,when the evaporation temperature rose from 5℃ to 15℃,the COP(coefficient of performance)increased by around 8%,although this could be increased by 2.3%–6.3%if the generator temperature decreases from 100℃ to 80℃.Moreover,the COP and exergetic performance for the HR-ARS is more significant at the lowest generator,condenser and evaporator temperatures,as well as at high efficiency in the solution heat exchanger,in comparison to ARS system.Furthermore,the COP and exergy performance for the HR-ARS system was improved by 2.57%to 3.11%and 0.22%to 0.7%,respectively,while the recovering condensation heat for generation is around 1.51%–3.76%lower than with the ARS.It also was found that for all ranges of evaporator and condenser temperatures,the COP for the HR-ARS system is around 3%higher than that obtained with the ARS at the three different generator temperatures here analyzed,while when the solution heat exchanger effectiveness was increased from 0.7–1.0,the total exergy destruction for the HR-ARS resulted be 3.24%–5.01%smaller than the ARS system.Finally,it can be concluded that the components with the most exergy destroyed in the systems(80%to 94%)are the generator and absorber.展开更多
A time series model is used in this paper to describe the progress of circulating direct condensation heat recovery of the compound condensing process (CCP) which is made of two water cooling condensing processes in s...A time series model is used in this paper to describe the progress of circulating direct condensation heat recovery of the compound condensing process (CCP) which is made of two water cooling condensing processes in series for a centrifugal chiller in the paper. A finite-time thermodynamics method is used to set up the time series simulation model. As a result, an upper bound of recoverable condensation heat for the compound condensing process is obtained which is in good agreement with experimental result. And the result is valuable and useful to optimization design of condensing heat recovery.展开更多
To a kind of centrifugal water chiller with R22 and about 1 745 kW of cooling capacity,a heat exchanger was added between the outlet of compressor and original condenser to get part of or all the condensing heat.Conde...To a kind of centrifugal water chiller with R22 and about 1 745 kW of cooling capacity,a heat exchanger was added between the outlet of compressor and original condenser to get part of or all the condensing heat.Condensing heat can be recovered by compound condensing method,which adopts air-cooling model +water-cooling model or water-cooling model +water-cooling model at the condensing side of the system.By exergy analysis and experiment research on compound condensing heat recovery of centrifugal chiller,the results are obtained that the capability of the whole system increases,the energy efficiency ratio(EER)becomes 3.2～5.0 from 2.2～3.4,which implies the EER increases about 1.0～1.5,the exergy efficiency increases about 10%,and the chiller runs more stably after reformation.展开更多
This paper presents a frame figure of the recovery system concerning waste heat of steam condensate. When steam phase changes into liquid state in the condenser, the heat equilibium equation, gas state equation, mass ...This paper presents a frame figure of the recovery system concerning waste heat of steam condensate. When steam phase changes into liquid state in the condenser, the heat equilibium equation, gas state equation, mass flow calculating equation of the jet steam and incondensable gas equation are established. The coupling function between condensate unit and recovery pump of the hot condensate with ejector is studied. The paper sets up the fluid continuity equation, heat equilibium equation and efficiency equation of the ejector and points out the technical key how the prevent hot condensate change into steam phase. When fluid passes from circulation loop through pump to export, the energy equations are obtained here. At last, signal figure of the applied examples are given and settle the techanical questions of the jet system are discussed.展开更多
In this study, the concept of a new seawater desalination method and equipment using liquid columns of seawater and desalinated fresh water, decompression boiling and evaporation, condensation, and recovery of condens...In this study, the concept of a new seawater desalination method and equipment using liquid columns of seawater and desalinated fresh water, decompression boiling and evaporation, condensation, and recovery of condensation latent heat are proposed. The equipment consists of seawater and freshwater columns approximately 10 m high with top spaces. The pressure of the top space, the evaporation and condensation area, of the seawater column, for example, is reduced approximately 30 mmHg (abs.) using the seawater column, after which it is heated from the general seawater temperature of 25°C to 30°C to boil and evaporate the seawater. The vapor is cooled by the seawater at approximately 25°C in a heat exchanger, and then, it is condensed and sent to the fresh water column. At this time, the condensation latent heat is recovered to preheat the newly flowing seawater. The evaporation or condensation rate, namely, the production rate of freshwater, by the new desalination equipment is also estimated by the results of the existing quadruplex effect vacuum evaporator used in the salt production industry. This new desalination method and its associated equipment also can be used to purify polluted water and waste water.展开更多
The paper shows a method of designing a heat exchanger recovering heat from the condensation of water vapour contained in flue gases. A heat exchanger condenses water vapour and SO2 （sulphur dioxide） in the presence...The paper shows a method of designing a heat exchanger recovering heat from the condensation of water vapour contained in flue gases. A heat exchanger condenses water vapour and SO2 （sulphur dioxide） in the presence of inert gases （CO2, CO, N2, O2） contained in flue gases. A mathematical model and a sample design of a heat exchanger were presented. The heat exchange is capable of recovering from a dozen or so to several dozen percent of heat from flue gases escaping into the atmosphere. A second advantage of the heat exchanger is the possibility to reduce the emissions of SO2 considerably. Depending on the parameters, it can be even a sevenfold reduction in the emissions. The main mathematical tool used for designing the condensing heat exchanger is the Colburn-Hougen method. The authors omitted that part of the method which requires iterative calculations. The Mollier diagram was used instead.展开更多
文摘In conventional absorption refrigeration systems(ARS),the heat from the condenser is usually rejected by the environment in place to be used in the system,so recuperating this is a good alternative to enhance the system’s performance.For instance,in this paper,an alternative ARS in which LiBr/Water is used as a refrigerant mixture,where part of condensing heat is recovered via the solution heat recovery generator absorption cycle(HR-ARS)was energy and exergy evaluated.The influence of generator,condenser and evaporator temperatures,as well as the efficiency of the solution heat exchanger on the coefficient of performance,exergy performance and exergy destroyed of the HR-ARS system,were analyzed and compared with the traditional ARS system at the same working conditions.The results showed an increase between 5.8%–6.3%on the COP and 3.7%–9.5%in the exergy efficiency when condenser/absorber temperature was reduced from 40℃ to 30℃.However,when the evaporation temperature rose from 5℃ to 15℃,the COP(coefficient of performance)increased by around 8%,although this could be increased by 2.3%–6.3%if the generator temperature decreases from 100℃ to 80℃.Moreover,the COP and exergetic performance for the HR-ARS is more significant at the lowest generator,condenser and evaporator temperatures,as well as at high efficiency in the solution heat exchanger,in comparison to ARS system.Furthermore,the COP and exergy performance for the HR-ARS system was improved by 2.57%to 3.11%and 0.22%to 0.7%,respectively,while the recovering condensation heat for generation is around 1.51%–3.76%lower than with the ARS.It also was found that for all ranges of evaporator and condenser temperatures,the COP for the HR-ARS system is around 3%higher than that obtained with the ARS at the three different generator temperatures here analyzed,while when the solution heat exchanger effectiveness was increased from 0.7–1.0,the total exergy destruction for the HR-ARS resulted be 3.24%–5.01%smaller than the ARS system.Finally,it can be concluded that the components with the most exergy destroyed in the systems(80%to 94%)are the generator and absorber.
文摘A time series model is used in this paper to describe the progress of circulating direct condensation heat recovery of the compound condensing process (CCP) which is made of two water cooling condensing processes in series for a centrifugal chiller in the paper. A finite-time thermodynamics method is used to set up the time series simulation model. As a result, an upper bound of recoverable condensation heat for the compound condensing process is obtained which is in good agreement with experimental result. And the result is valuable and useful to optimization design of condensing heat recovery.
文摘To a kind of centrifugal water chiller with R22 and about 1 745 kW of cooling capacity,a heat exchanger was added between the outlet of compressor and original condenser to get part of or all the condensing heat.Condensing heat can be recovered by compound condensing method,which adopts air-cooling model +water-cooling model or water-cooling model +water-cooling model at the condensing side of the system.By exergy analysis and experiment research on compound condensing heat recovery of centrifugal chiller,the results are obtained that the capability of the whole system increases,the energy efficiency ratio(EER)becomes 3.2～5.0 from 2.2～3.4,which implies the EER increases about 1.0～1.5,the exergy efficiency increases about 10%,and the chiller runs more stably after reformation.
文摘This paper presents a frame figure of the recovery system concerning waste heat of steam condensate. When steam phase changes into liquid state in the condenser, the heat equilibium equation, gas state equation, mass flow calculating equation of the jet steam and incondensable gas equation are established. The coupling function between condensate unit and recovery pump of the hot condensate with ejector is studied. The paper sets up the fluid continuity equation, heat equilibium equation and efficiency equation of the ejector and points out the technical key how the prevent hot condensate change into steam phase. When fluid passes from circulation loop through pump to export, the energy equations are obtained here. At last, signal figure of the applied examples are given and settle the techanical questions of the jet system are discussed.
文摘In this study, the concept of a new seawater desalination method and equipment using liquid columns of seawater and desalinated fresh water, decompression boiling and evaporation, condensation, and recovery of condensation latent heat are proposed. The equipment consists of seawater and freshwater columns approximately 10 m high with top spaces. The pressure of the top space, the evaporation and condensation area, of the seawater column, for example, is reduced approximately 30 mmHg (abs.) using the seawater column, after which it is heated from the general seawater temperature of 25°C to 30°C to boil and evaporate the seawater. The vapor is cooled by the seawater at approximately 25°C in a heat exchanger, and then, it is condensed and sent to the fresh water column. At this time, the condensation latent heat is recovered to preheat the newly flowing seawater. The evaporation or condensation rate, namely, the production rate of freshwater, by the new desalination equipment is also estimated by the results of the existing quadruplex effect vacuum evaporator used in the salt production industry. This new desalination method and its associated equipment also can be used to purify polluted water and waste water.
文摘The paper shows a method of designing a heat exchanger recovering heat from the condensation of water vapour contained in flue gases. A heat exchanger condenses water vapour and SO2 （sulphur dioxide） in the presence of inert gases （CO2, CO, N2, O2） contained in flue gases. A mathematical model and a sample design of a heat exchanger were presented. The heat exchange is capable of recovering from a dozen or so to several dozen percent of heat from flue gases escaping into the atmosphere. A second advantage of the heat exchanger is the possibility to reduce the emissions of SO2 considerably. Depending on the parameters, it can be even a sevenfold reduction in the emissions. The main mathematical tool used for designing the condensing heat exchanger is the Colburn-Hougen method. The authors omitted that part of the method which requires iterative calculations. The Mollier diagram was used instead.
