Directly measuring the oxidative heat release intensity at low temperatures is difficult at present.We developed a new method based on heat conduction theory that directly measures heat release intensity of loose coal...Directly measuring the oxidative heat release intensity at low temperatures is difficult at present.We developed a new method based on heat conduction theory that directly measures heat release intensity of loose coal at low temperatures.Using this method, we calculated the oxidative heat release intensity of differently sized loose coals by comparing the temperature rise of the coal in nitrogen or an air environment.The results show that oxidation heat release intensity of Shenhua coal sized 0～15 mm is 0.001～0.03 W/m3 at 30～90 °C and increases with increasing temperature.The heat release intensity at a given temperature is larger for smaller sized coal.The temperature effect on heat release intensity is muted as the coal size increases.At lower temperature the change in heat release intensity as a function of size becomes smaller.These results show that the test system is usable for practical applications and is easy to operate and is capable of measuring mass samples.展开更多
In order to popularize the use of the solar-water heaters, especially in the residential and tertiary sectors with the third world, it appears to be necessary to reduce their cost while improving their performances. I...In order to popularize the use of the solar-water heaters, especially in the residential and tertiary sectors with the third world, it appears to be necessary to reduce their cost while improving their performances. It is the object of this integrated storage collector thus created and tested in the south of Tunisia. It is simply made up of a tank playing the double part of solar absorber and storage tank of warm water, of a glazing to profit from the greenhouse effect and of an insulating case. Its measured energy performances, by the method of input-output proves its effectiveness to produce hot water, in spite of its simplicity of manufacture, usage and maintenance. Indeed a temperature of water exceeding 70?C is reached towards the afternoon True Solar Time, and for an efficiency of 7%. Thus, this type of collector with integrated storage is entirely satisfactory and could be available to larger mass.展开更多
Arranging heat exchanger in filling body to extract geothermal energy is an effective way to alleviate the problems of high ground pressure and high ground temperature in deep resource exploitation.Filling body with c...Arranging heat exchanger in filling body to extract geothermal energy is an effective way to alleviate the problems of high ground pressure and high ground temperature in deep resource exploitation.Filling body with casing heat exchanger was acted as research object,encapsulating phase change materials(PCMs)in annular space.During heat storage and heat release process,the effects of different PCMs on temperature distribution,phase-change process and heat transfer performance were studied.The result indicates:During heat storage process,the temperature increases rapidly and the melting process is accelerated for the position closer surrounding rock.CaCl_(2)·6H_(2)O/EG can make filling body complete heat storage process in the shortest time because of its good thermal diffusivity.The heat storage capacity of PCMs backfill is significantly higher than that of ordinary backfill;it increases by 36.6%-67.3%at heat storage of 10 h.During heat release process,the closer to the heat exchange tube,the greater the temperature drop in filling body.The maximum value of heat release rate and heat release capacity is in CaCl_(2)·6H_(2)O/EG backfill,it can release 116.4%more heat than RT35backfill after heat release of 12 h,the maximum value of effectiveness and its heat transfer rate also is in CaCl_(2)·6H_(2)O/EG backfill.This paper provides the basic data for the selection of PCMs in phase-change thermal storage filling body.展开更多
基金Projects 50474067 supported by the National Natural Science Foundation of China2007KF11 by the State Key Laboratory of Coal Resources and Safety Mining
文摘Directly measuring the oxidative heat release intensity at low temperatures is difficult at present.We developed a new method based on heat conduction theory that directly measures heat release intensity of loose coal at low temperatures.Using this method, we calculated the oxidative heat release intensity of differently sized loose coals by comparing the temperature rise of the coal in nitrogen or an air environment.The results show that oxidation heat release intensity of Shenhua coal sized 0～15 mm is 0.001～0.03 W/m3 at 30～90 °C and increases with increasing temperature.The heat release intensity at a given temperature is larger for smaller sized coal.The temperature effect on heat release intensity is muted as the coal size increases.At lower temperature the change in heat release intensity as a function of size becomes smaller.These results show that the test system is usable for practical applications and is easy to operate and is capable of measuring mass samples.
文摘In order to popularize the use of the solar-water heaters, especially in the residential and tertiary sectors with the third world, it appears to be necessary to reduce their cost while improving their performances. It is the object of this integrated storage collector thus created and tested in the south of Tunisia. It is simply made up of a tank playing the double part of solar absorber and storage tank of warm water, of a glazing to profit from the greenhouse effect and of an insulating case. Its measured energy performances, by the method of input-output proves its effectiveness to produce hot water, in spite of its simplicity of manufacture, usage and maintenance. Indeed a temperature of water exceeding 70?C is reached towards the afternoon True Solar Time, and for an efficiency of 7%. Thus, this type of collector with integrated storage is entirely satisfactory and could be available to larger mass.
基金supported by the National Natural Science Foundation of China(Nos.51974225,51674188,51874229,51504182,51904224,51904225,51704229)Shaanxi Innovative Talents Cultivate Program-New-star Plan of Science and Technology(No.2018KJXX-083)+4 种基金Natural Science Basic Research Plan of Shaanxi Province of China(Nos.2018JM5161,2018JQ5183,2015JQ5187,2019JM-074)Scientific Research Program funded by the Shaanxi Provincial Education Department(Nos.15JK1466,19JK0543)China Postdoctoral Science Foundation(No.2015M582685)Outstanding Youth Science Fund of Xi’an University of Science and Technology(No.2018YQ2-01)the Scientific Research Program funded by Xi’an Science and Technology Bureau(No.201805036YD14CG20)。
文摘Arranging heat exchanger in filling body to extract geothermal energy is an effective way to alleviate the problems of high ground pressure and high ground temperature in deep resource exploitation.Filling body with casing heat exchanger was acted as research object,encapsulating phase change materials(PCMs)in annular space.During heat storage and heat release process,the effects of different PCMs on temperature distribution,phase-change process and heat transfer performance were studied.The result indicates:During heat storage process,the temperature increases rapidly and the melting process is accelerated for the position closer surrounding rock.CaCl_(2)·6H_(2)O/EG can make filling body complete heat storage process in the shortest time because of its good thermal diffusivity.The heat storage capacity of PCMs backfill is significantly higher than that of ordinary backfill;it increases by 36.6%-67.3%at heat storage of 10 h.During heat release process,the closer to the heat exchange tube,the greater the temperature drop in filling body.The maximum value of heat release rate and heat release capacity is in CaCl_(2)·6H_(2)O/EG backfill,it can release 116.4%more heat than RT35backfill after heat release of 12 h,the maximum value of effectiveness and its heat transfer rate also is in CaCl_(2)·6H_(2)O/EG backfill.This paper provides the basic data for the selection of PCMs in phase-change thermal storage filling body.
