Theoretical and experimental analysis of a new refrigerant mixture BY-3 was conducted based on a single-stage vapor compression refrigeration system. The water-water heat pump system used BY-3 to produce hot water whe...Theoretical and experimental analysis of a new refrigerant mixture BY-3 was conducted based on a single-stage vapor compression refrigeration system. The water-water heat pump system used BY-3 to produce hot water when the low temperature was 20 ℃. The following results were obtained: the highest temperature at the condenser outlet reached about 85 ℃; when the difference between the water temperatures at the condenser outlet and the evaporator inlet was less than 40 ℃, the coefficient of performance (COP) was larger than 4; when the difference reached 55 ℃, the COP still kept 3; the discharge temperature of BY-3 was lower than 100 ℃, and the refrigerant vapor pressure kept lower than 1.8 MPa. When the water temperature at the condenser outlet reached over 85 ℃, nearly a 5 ℃ superheating temperature was maintained.展开更多
Based on the structure of the long fiber laser (YDCFLs) with different pump schemes using high pump power, the nonlinear coupled and heat dissipation equations are solved numerically. Using the finite-difference metho...Based on the structure of the long fiber laser (YDCFLs) with different pump schemes using high pump power, the nonlinear coupled and heat dissipation equations are solved numerically. Using the finite-difference method, we have determined the temperature distribution along the radial and axial directions of the fiber laser (YDCFLs) for the forward pump schemes of 200 W with reflection Rp2, backward pump schemes of 200 W with reflection Rp1 and for bidirectional pump scheme of 100 W each side. The results are: the temperature distribution for bidirectional pump mode is more even than that for forward pump with reflection Rp2 and than that for backward pump with reflection Rp1. The results show that the maximum temperature difference between different schemes is 57.51°C, and when the air-clad width decreases, the temperature in the core regions also decreases and does not affect to the cladding radius regions. We summarize that the temperature in the core and in cladding radius regions decreases when the outer radius cladding increases.展开更多
With the increasing environmental concern on global warming, hydrofluoro-olefin (HFOs), possessing low GWP, has attracted great attention of many researchers recently. In this study, non-azeotropic mixtures composed o...With the increasing environmental concern on global warming, hydrofluoro-olefin (HFOs), possessing low GWP, has attracted great attention of many researchers recently. In this study, non-azeotropic mixtures composed of HFOs (HFO-1234yf, HFO-1234ze(z), HFO-1234ze(e) and HFO-1234zf) are developed to substitute for HFC-134a and CFC-114 in air-conditioning and high-temperature heat pump systems, respectively. The cycle performances were evaluated by an improved theoretical cy-cle evaluation methodology. The results showed that all the mixtures proposed herein were favorable refrigerants with excel-lent thermodynamic cycle performances. M1A presented lower discharge temperature and pressure ratio and higher COPc than that of HFC-134a. The volumetric cooling capacity was similar to HFC-134a. It can be served as a good environmentally friendly alternative to replace HFC-134a. M3H delivered similar discharge temperature as CFC-114 did. And the COPh was 3% higher. It exhibits excellent cycle performance in high-temperature heat pump and is a promising refrigerant to substitute for CFC-114. And the gliding temperature differences enable them to exhibit better coefficient of performance by matching the sink/source temperature in practice. Because the toxicity, flammability and other properties are not investigated in detail, ex-tensive toxicity and flammability testing needs to be conducted before they are used in a particular application.展开更多
目前中国仍有部分工业园区采用供电、供热、供气等各种能源供应系统单独规划和运行的方式,导致大量工业余热被浪费,系统能效低、碳排放高。为了充分利用工业余热并提高系统运行能效,提出一种含高温蒸汽热泵(high temperature heat pump,...目前中国仍有部分工业园区采用供电、供热、供气等各种能源供应系统单独规划和运行的方式,导致大量工业余热被浪费,系统能效低、碳排放高。为了充分利用工业余热并提高系统运行能效,提出一种含高温蒸汽热泵(high temperature heat pump,HTHP)的工业园区综合能源系统(integrated energy system,IES)双层优化模型。首先,构建含HTHP的工业园区综合能源系统架构。其次,针对IES能效较低的问题,利用余热的梯级利用原则与多能协同原则,建立含HTHP的综合能源系统调度策略。再次,建立包含设备容量规划优化与运行优化的双层优化模型,并提出优化模型的求解方法。最后,通过西北地区一个化工园区的实例分析,验证了所提方法的有效性。展开更多
为解决低温余热资源过剩与高温用热需求紧缺之间的矛盾,设计了一套基于准二级压缩的高温热泵机组,理论分析循环流程并进行优化设计,采用闪蒸器与回热器组合提高机组性能,开展了机组的性能实验,以制热量、制热COP、[火用]效率、冷凝压力...为解决低温余热资源过剩与高温用热需求紧缺之间的矛盾,设计了一套基于准二级压缩的高温热泵机组,理论分析循环流程并进行优化设计,采用闪蒸器与回热器组合提高机组性能,开展了机组的性能实验,以制热量、制热COP、[火用]效率、冷凝压力、排气温度为性能指标,在冷凝器出水温度为85~120℃,蒸发器进水温度为50、60、70℃工况下,对机组性能进行分析。实测机组性能与理论计算结果吻合,蒸发器进水温度为49.8℃,冷凝器出水温度为118.1℃,机组制热量可达916.3 k W,制热COP为2.51,[火用]效率为46.3%,机组冷凝压力为1.8 MPa,排气温度为137℃,符合机组安全运行的要求。展开更多
In China, directly dropping high temperature refrigerant into conventional compressor is considered as a dominant technical route for development of moderately high temperature heat pump. Based on this route, selectio...In China, directly dropping high temperature refrigerant into conventional compressor is considered as a dominant technical route for development of moderately high temperature heat pump. Based on this route, selection criteria for high temperature refrigerant were presented with consideration of several influencing factors. Moreover, a set of research methods were built including theoretical calculations and experimental tests. Four high temperature refrigerants from HTR01 to HTR04 were compared and analyzed. In results, firstly, HTR03 and HTR04 belonging to non-ozone depleting refrigerants could bring outstanding environmental benefits; secondly, the condenser outlet water efficiently generated by heat pump using high temperature refrigerants could cover 60°C–90°C;; finally, the feasibility of the technical route and the research methods were proved.展开更多
The high‐temperature superconducting(HTS)dynamo enables injection of large DC currents into a superconducting coil,without the need for thermally‐inefficient current leads.Because of this important advantage,there i...The high‐temperature superconducting(HTS)dynamo enables injection of large DC currents into a superconducting coil,without the need for thermally‐inefficient current leads.Because of this important advantage,there is significant interest in using such technology to energise superconducting coils in superconducting rotating machines and NMR/MRI magnets.Despite the extensive experimental work carried out over the past decade,there was–until very recently–considerable confusion and debate regarding the physical origin of the HTS dynamo’s DC output voltage.Numerical modelling has played a key role in elucidating the underlying physics of such devices and several different numerical models have now been developed as useful and cost‐effective tools to not only explain and further examine experimental results,but also optimise and improve dynamo designs.This review summarises all of the developments in this important area over recent years,including modelling the open‐circuit voltage behaviour in 2D and 3D,the definition of a new benchmark problem for the HTS modelling community,investigating key dynamo parameters,modelling dynamic coil charging behaviour and calculating losses.A view towards the future is provided,including the outstanding challenges and the developments required to address these.展开更多
基金Supported by Major State Basic Research Development Program of China ("973" Program, No. 2009CB219907)the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT0936)
文摘Theoretical and experimental analysis of a new refrigerant mixture BY-3 was conducted based on a single-stage vapor compression refrigeration system. The water-water heat pump system used BY-3 to produce hot water when the low temperature was 20 ℃. The following results were obtained: the highest temperature at the condenser outlet reached about 85 ℃; when the difference between the water temperatures at the condenser outlet and the evaporator inlet was less than 40 ℃, the coefficient of performance (COP) was larger than 4; when the difference reached 55 ℃, the COP still kept 3; the discharge temperature of BY-3 was lower than 100 ℃, and the refrigerant vapor pressure kept lower than 1.8 MPa. When the water temperature at the condenser outlet reached over 85 ℃, nearly a 5 ℃ superheating temperature was maintained.
文摘Based on the structure of the long fiber laser (YDCFLs) with different pump schemes using high pump power, the nonlinear coupled and heat dissipation equations are solved numerically. Using the finite-difference method, we have determined the temperature distribution along the radial and axial directions of the fiber laser (YDCFLs) for the forward pump schemes of 200 W with reflection Rp2, backward pump schemes of 200 W with reflection Rp1 and for bidirectional pump scheme of 100 W each side. The results are: the temperature distribution for bidirectional pump mode is more even than that for forward pump with reflection Rp2 and than that for backward pump with reflection Rp1. The results show that the maximum temperature difference between different schemes is 57.51°C, and when the air-clad width decreases, the temperature in the core regions also decreases and does not affect to the cladding radius regions. We summarize that the temperature in the core and in cladding radius regions decreases when the outer radius cladding increases.
基金supported by the National Natural Science Foundation of China (Grant No. 50976079)Science and Technology Support Key Project of Tianjin (Grant No. 10ZCKFGX01700)
文摘With the increasing environmental concern on global warming, hydrofluoro-olefin (HFOs), possessing low GWP, has attracted great attention of many researchers recently. In this study, non-azeotropic mixtures composed of HFOs (HFO-1234yf, HFO-1234ze(z), HFO-1234ze(e) and HFO-1234zf) are developed to substitute for HFC-134a and CFC-114 in air-conditioning and high-temperature heat pump systems, respectively. The cycle performances were evaluated by an improved theoretical cy-cle evaluation methodology. The results showed that all the mixtures proposed herein were favorable refrigerants with excel-lent thermodynamic cycle performances. M1A presented lower discharge temperature and pressure ratio and higher COPc than that of HFC-134a. The volumetric cooling capacity was similar to HFC-134a. It can be served as a good environmentally friendly alternative to replace HFC-134a. M3H delivered similar discharge temperature as CFC-114 did. And the COPh was 3% higher. It exhibits excellent cycle performance in high-temperature heat pump and is a promising refrigerant to substitute for CFC-114. And the gliding temperature differences enable them to exhibit better coefficient of performance by matching the sink/source temperature in practice. Because the toxicity, flammability and other properties are not investigated in detail, ex-tensive toxicity and flammability testing needs to be conducted before they are used in a particular application.
文摘目前中国仍有部分工业园区采用供电、供热、供气等各种能源供应系统单独规划和运行的方式,导致大量工业余热被浪费,系统能效低、碳排放高。为了充分利用工业余热并提高系统运行能效,提出一种含高温蒸汽热泵(high temperature heat pump,HTHP)的工业园区综合能源系统(integrated energy system,IES)双层优化模型。首先,构建含HTHP的工业园区综合能源系统架构。其次,针对IES能效较低的问题,利用余热的梯级利用原则与多能协同原则,建立含HTHP的综合能源系统调度策略。再次,建立包含设备容量规划优化与运行优化的双层优化模型,并提出优化模型的求解方法。最后,通过西北地区一个化工园区的实例分析,验证了所提方法的有效性。
文摘为解决低温余热资源过剩与高温用热需求紧缺之间的矛盾,设计了一套基于准二级压缩的高温热泵机组,理论分析循环流程并进行优化设计,采用闪蒸器与回热器组合提高机组性能,开展了机组的性能实验,以制热量、制热COP、[火用]效率、冷凝压力、排气温度为性能指标,在冷凝器出水温度为85~120℃,蒸发器进水温度为50、60、70℃工况下,对机组性能进行分析。实测机组性能与理论计算结果吻合,蒸发器进水温度为49.8℃,冷凝器出水温度为118.1℃,机组制热量可达916.3 k W,制热COP为2.51,[火用]效率为46.3%,机组冷凝压力为1.8 MPa,排气温度为137℃,符合机组安全运行的要求。
基金Supported by Program for New Century Excellent Talents in University (Grand No. NCET-04-0078)
文摘In China, directly dropping high temperature refrigerant into conventional compressor is considered as a dominant technical route for development of moderately high temperature heat pump. Based on this route, selection criteria for high temperature refrigerant were presented with consideration of several influencing factors. Moreover, a set of research methods were built including theoretical calculations and experimental tests. Four high temperature refrigerants from HTR01 to HTR04 were compared and analyzed. In results, firstly, HTR03 and HTR04 belonging to non-ozone depleting refrigerants could bring outstanding environmental benefits; secondly, the condenser outlet water efficiently generated by heat pump using high temperature refrigerants could cover 60°C–90°C;; finally, the feasibility of the technical route and the research methods were proved.
文摘The high‐temperature superconducting(HTS)dynamo enables injection of large DC currents into a superconducting coil,without the need for thermally‐inefficient current leads.Because of this important advantage,there is significant interest in using such technology to energise superconducting coils in superconducting rotating machines and NMR/MRI magnets.Despite the extensive experimental work carried out over the past decade,there was–until very recently–considerable confusion and debate regarding the physical origin of the HTS dynamo’s DC output voltage.Numerical modelling has played a key role in elucidating the underlying physics of such devices and several different numerical models have now been developed as useful and cost‐effective tools to not only explain and further examine experimental results,but also optimise and improve dynamo designs.This review summarises all of the developments in this important area over recent years,including modelling the open‐circuit voltage behaviour in 2D and 3D,the definition of a new benchmark problem for the HTS modelling community,investigating key dynamo parameters,modelling dynamic coil charging behaviour and calculating losses.A view towards the future is provided,including the outstanding challenges and the developments required to address these.
