The performance of a direct-expansion ground-source heat pump（DX GSHP）system is theoretically analyzed.Compared with the conventional ground-source heat pump（GSHP）,the DX GSHP has a lower condensing temperature in...The performance of a direct-expansion ground-source heat pump（DX GSHP）system is theoretically analyzed.Compared with the conventional ground-source heat pump（GSHP）,the DX GSHP has a lower condensing temperature in the cooling mode and a higher evaporating temperature in the heating mode,and the ground heat exchanger（GHE）in the DX GSHP has a low thermal resistance.Therefore,the coefficient of performance（COP）of the DX GSHP is higher than that of the GSHP.In addition,the system performance of the DX GSHP system is higher than that of the conventional GSHP system because there are no secondary solution loops and water circulating pumps in the DX GSHP system.The experimental energy performance of the DX GSHP system is also investigated based on the actual operational data.The tested DX GSHP system is installed in Xiangtan,China.The U-vertical GHE of the DX GSHP is buried in a water well.The length and the outside nominal diameter of the GHE are 42 m and 12.7 mm,respectively.The experimental results show that the maximum（COP）and the average COP of the DX GSHP system in the heating mode are 5.95 and 4.72,respectively.展开更多
Resource-based cities are the most important players in responding to climate change and achieving low carbon development in China.An analysis of relevant data(such as the energy consumption)showed an inter-city diffe...Resource-based cities are the most important players in responding to climate change and achieving low carbon development in China.An analysis of relevant data(such as the energy consumption)showed an inter-city differentiation of CO2 emissions from energy consumption,and suggested an influence of the Industrial Enterprises above Designated Size(IEDS)in resource-based industrial cities at the prefecture level and above in different regions.Then by geographical detector technology,the sizes of each influencing mechanism on CO2 emissions from energy consumption of the IEDS were probed.This analysis showed that significant spatial differences exist for CO2 emissions from energy consumption and revealed several factors which influence the IEDS in resource-based cities.(1)In terms of unit employment,Eastern and Western resource-based cities are above the overall level of all resource-based cities;and only Coal resource-based cities far exceeded the overall level among all of the cities in the analysis.(2)In terms of unit gross industrial output value,the Eastern,Central and Western resources-based cities are all above the overall level for all the cities.Here also,only Coal resource-based cities far exceeded the overall level of all resources-based cities.Economic scale and energy structure are the main factors influencing CO2 emissions from energy consumption of the IEDS in resource-based cities.The factors influencing CO2 emissions in different regions and types of resource-based cities show significant spatial variations,and the degree of influence that any given factor exerts varies among different regions and types of resource-based cities.Therefore,individualized recommendations should be directed to different regions and types of resource-based cities,so that the strategies and measures of industrial low carbon and transformation should vary greatly according to the specific conditions that exist in each city.展开更多
基金The National Key Technologies R&D Program of Chinaduring the 11th Five-Year Plan Period(No.2006BAJ04B04,2006BAJ04A05,2006BAJ04A13)
文摘The performance of a direct-expansion ground-source heat pump（DX GSHP）system is theoretically analyzed.Compared with the conventional ground-source heat pump（GSHP）,the DX GSHP has a lower condensing temperature in the cooling mode and a higher evaporating temperature in the heating mode,and the ground heat exchanger（GHE）in the DX GSHP has a low thermal resistance.Therefore,the coefficient of performance（COP）of the DX GSHP is higher than that of the GSHP.In addition,the system performance of the DX GSHP system is higher than that of the conventional GSHP system because there are no secondary solution loops and water circulating pumps in the DX GSHP system.The experimental energy performance of the DX GSHP system is also investigated based on the actual operational data.The tested DX GSHP system is installed in Xiangtan,China.The U-vertical GHE of the DX GSHP is buried in a water well.The length and the outside nominal diameter of the GHE are 42 m and 12.7 mm,respectively.The experimental results show that the maximum（COP）and the average COP of the DX GSHP system in the heating mode are 5.95 and 4.72,respectively.
基金The Ministry of Education on Cultivate Project Fund of Philosophy and Social Science Research Development Report(13JBGP004)
文摘Resource-based cities are the most important players in responding to climate change and achieving low carbon development in China.An analysis of relevant data(such as the energy consumption)showed an inter-city differentiation of CO2 emissions from energy consumption,and suggested an influence of the Industrial Enterprises above Designated Size(IEDS)in resource-based industrial cities at the prefecture level and above in different regions.Then by geographical detector technology,the sizes of each influencing mechanism on CO2 emissions from energy consumption of the IEDS were probed.This analysis showed that significant spatial differences exist for CO2 emissions from energy consumption and revealed several factors which influence the IEDS in resource-based cities.(1)In terms of unit employment,Eastern and Western resource-based cities are above the overall level of all resource-based cities;and only Coal resource-based cities far exceeded the overall level among all of the cities in the analysis.(2)In terms of unit gross industrial output value,the Eastern,Central and Western resources-based cities are all above the overall level for all the cities.Here also,only Coal resource-based cities far exceeded the overall level of all resources-based cities.Economic scale and energy structure are the main factors influencing CO2 emissions from energy consumption of the IEDS in resource-based cities.The factors influencing CO2 emissions in different regions and types of resource-based cities show significant spatial variations,and the degree of influence that any given factor exerts varies among different regions and types of resource-based cities.Therefore,individualized recommendations should be directed to different regions and types of resource-based cities,so that the strategies and measures of industrial low carbon and transformation should vary greatly according to the specific conditions that exist in each city.
