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
An ultra-low-power,256-bit EEPROM is designed and implemented in a Chartered 0.35μm EEPROM process. The read state power consumption is optimized using a new sense amplifier structure and an optimized control circuit...An ultra-low-power,256-bit EEPROM is designed and implemented in a Chartered 0.35μm EEPROM process. The read state power consumption is optimized using a new sense amplifier structure and an optimized control circuit. Block programming/erasing is achieved using an improved control circuit. An on silicon program/erase/read access time measurement design is given. For a power supply voltage of 1.8V,an average power consumption of 68 and 0.6μA for the program/erase and read operations,respectively,can be achieved at 640kHz.展开更多
A new ground source heat pump system combined with radiant heating/cooling is proposed, and the principles and the advantages of the system are analyzed. A demonstration of the system is applied to a rebuilt building...A new ground source heat pump system combined with radiant heating/cooling is proposed, and the principles and the advantages of the system are analyzed. A demonstration of the system is applied to a rebuilt building： Xijindu exhibition hall, which is located in Zhenjiang city in China. Numerical studies on the thermal comfort and energy consumption of the system are carded out by using TRNSYS software. The results indicate that the system with the radiant floor method or the radiant ceiling method shows good thermal comfort without mechanical ventilation in winter. However, the system with either of the methods should add mechanical ventilation to ensure good comfort in summer. At the same level of thermal comfort, it can also be found that the annual energy consumption of the radiant ceiling system is less than that of the radiant floor system.展开更多
A new,low-cost RFID tag analog front-end compatible with ISO 14443A and ISO 14443B is presented. By substituting conventional multi-circle antenna with single-circle antenna, the package cost of the tag is greatly red...A new,low-cost RFID tag analog front-end compatible with ISO 14443A and ISO 14443B is presented. By substituting conventional multi-circle antenna with single-circle antenna, the package cost of the tag is greatly reduced. Based on this exasperate antenna performance,a new rectifier with high power conversion efficiency and low turn-on voltage is presented. The circuit is implemented in an SMIC 0.18μm EEPROM process. Measurement results show that with a 120kΩ load,the power conversion efficiency reaches as high as 36%. For a sinusoidal wave with magnitude of 0. 5V, the output DC voltage reaches IV,which is high enough for RFID tags. The read distance is as far as 22cm.展开更多
The research goal is to develop a new solar water heater system(SWHS) that uses a solar bubble pump instead of an electric pump.The pump is powered by the steam produced from an evacuated tube collector.Therefore,heat...The research goal is to develop a new solar water heater system(SWHS) that uses a solar bubble pump instead of an electric pump.The pump is powered by the steam produced from an evacuated tube collector.Therefore,heat could be transferred downward from the collector to a hot water storage tank.The designed system consists of two sets of heat-pipe evacuated tube collectors,a solar bubble pump installed at an upper level and a water storage tank with a heat exchanger at a lower level.Discharge heads of 1 and 5 m were tested.The bubble pump could operate at the collector temperature of about 90-100 ℃ and vapor gage pressure of 80-90 kPa.It is found that water circulation within the SWHS depends on the incident solar intensity and system discharge head.Experimental investigations are conducted to obtain the system thermal efficiencies from the hourly,daily and long-term performance tests.The thermal performance of the proposed system is compared with conventional solar water heaters.The results show that the proposed system achieves system characteristic efficiency of 10% higher than that of the conventional systems using electric pump if taking the consumption of electric power into account.And the former is a zero carbon system.展开更多
The coupling-wave equations of photorefractive wave mixing processes including two-and four-wave mixing are expressed as an unified matrix equation in the undepleted pump approximation.The lossless general solution of...The coupling-wave equations of photorefractive wave mixing processes including two-and four-wave mixing are expressed as an unified matrix equation in the undepleted pump approximation.The lossless general solution of the matrix equation is obtained.The previous formulas of five wave-mixing processes in the undepleted pump are derived from the solution when their boundary conditions are used.展开更多
Reducing CO2 emissions and restraining dependence on nuclear power generation are serious concerns in the prevention of global warming since the Great East Japan Earthquake. To do so, it is necessary to use and expand...Reducing CO2 emissions and restraining dependence on nuclear power generation are serious concerns in the prevention of global warming since the Great East Japan Earthquake. To do so, it is necessary to use and expand natural renewable energy source such as solar energy and to promote energy conservation. However, in high-latitude regions, it is difficult to directly and effectively use solar power due to on insufficient amount of solar radiation. If steam can be generated from warm water at less than 373 K, it is possible to obtain steam by solar water heaters from weak solar radiation and industrial waste warm water without the consumption of any fossil fuels. In this study, the authors have been developing a system which generates steam over 423 K from warm water at less than 373 K using an adsorption heat pump with zeolite. Therefore, bench-scale equipment which generates steam continuously and the experimental results are mentioned.展开更多
ASHP （air source heat pump） water heater is a renewable and energy efficient device used for sanitary hot water production. The system comprises of a storage tank and heat pump connected by pipes. These major units ...ASHP （air source heat pump） water heater is a renewable and energy efficient device used for sanitary hot water production. The system comprises of a storage tank and heat pump connected by pipes. These major units can either be compact as in the integrated model or split as in the retro-fit model. In this research, the analysis of energy losses was performed using SIRAC （the Southern African refrigeration and air conditioning） residential split type heat pump of 1.2 kW input power to retrofit a 200 liter high pressure kwikhot storage tank without hot water being drawn off for the entire monitoring period. Likewise to experimentally determine the losses DAS （data acquisition system） was designed and built to measure Ta （ambient temperature; RH-relative humidity）, RH, To （ASHP outlet water temperature）, Ti （ASHP inlet water temperature） and Vh. （volume of water heated by ASHP unit）.The results showed that the heat energy gain to compensate standby losses could range from 1.8 kWh to 2.1 kWh with the corresponding electrical energy used by ASHP water heater ranging from 0.55 kWh to 0.66 kWh. The standby losses depend primarily on the Vh, the Ta and the RH while the influence of （To - Ti） is secondary. The results can be of valuable interest to manufacturer of retrofit ASHP unit for hot water production when matching the electrical energy required to compensate for the standby losses.展开更多
Design method for a mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. The...Design method for a mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Then, a semi-open impeller for the mini centrifugal pump with 55mm impeller diameter is adopted in this research to take simplicity and maintenance into consideration. Splitter blades are adopted in this research to improve the performance and internal flow condition of mini centrifugal pump having large blade outlet angle. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on the performance and internal flow condition of the mini centrifugal pump. A three dimensional steady numerical flow analysis is conducted to analyze rotor, volute efficiency and loss caused by a vortex. It is clarified from the experimental results that the performance of the mini centrifugal pump is improved by the effect of the splitter blades. Flow condition at outlet of the rotor becomes uniform and back flow regions are suppressed in the case with the splitter blades.Further, the volute efficiency increases and the vortex loss decreases. In the present paper, the performance of the mini centrifugal pump is shown and the flow condition is clarified with the results of the experiment and the numerical flow analysis. Furthermore, the performance analyses of the mini centrifugal pumps with and without the splitter blades are conducted.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.
文摘An ultra-low-power,256-bit EEPROM is designed and implemented in a Chartered 0.35μm EEPROM process. The read state power consumption is optimized using a new sense amplifier structure and an optimized control circuit. Block programming/erasing is achieved using an improved control circuit. An on silicon program/erase/read access time measurement design is given. For a power supply voltage of 1.8V,an average power consumption of 68 and 0.6μA for the program/erase and read operations,respectively,can be achieved at 640kHz.
基金The National Natural Science Foundation of China(No. 51036001 )the Natural Science Foundation of Jiangsu Province(No. BK2010043)
文摘A new ground source heat pump system combined with radiant heating/cooling is proposed, and the principles and the advantages of the system are analyzed. A demonstration of the system is applied to a rebuilt building： Xijindu exhibition hall, which is located in Zhenjiang city in China. Numerical studies on the thermal comfort and energy consumption of the system are carded out by using TRNSYS software. The results indicate that the system with the radiant floor method or the radiant ceiling method shows good thermal comfort without mechanical ventilation in winter. However, the system with either of the methods should add mechanical ventilation to ensure good comfort in summer. At the same level of thermal comfort, it can also be found that the annual energy consumption of the radiant ceiling system is less than that of the radiant floor system.
文摘A new,low-cost RFID tag analog front-end compatible with ISO 14443A and ISO 14443B is presented. By substituting conventional multi-circle antenna with single-circle antenna, the package cost of the tag is greatly reduced. Based on this exasperate antenna performance,a new rectifier with high power conversion efficiency and low turn-on voltage is presented. The circuit is implemented in an SMIC 0.18μm EEPROM process. Measurement results show that with a 120kΩ load,the power conversion efficiency reaches as high as 36%. For a sinusoidal wave with magnitude of 0. 5V, the output DC voltage reaches IV,which is high enough for RFID tags. The read distance is as far as 22cm.
基金Project(2011-0021376) supported by Basic Science Program through the National Research Foundation (NRF) Funded by the Ministry of Education,Science and Technology of Korea
文摘The research goal is to develop a new solar water heater system(SWHS) that uses a solar bubble pump instead of an electric pump.The pump is powered by the steam produced from an evacuated tube collector.Therefore,heat could be transferred downward from the collector to a hot water storage tank.The designed system consists of two sets of heat-pipe evacuated tube collectors,a solar bubble pump installed at an upper level and a water storage tank with a heat exchanger at a lower level.Discharge heads of 1 and 5 m were tested.The bubble pump could operate at the collector temperature of about 90-100 ℃ and vapor gage pressure of 80-90 kPa.It is found that water circulation within the SWHS depends on the incident solar intensity and system discharge head.Experimental investigations are conducted to obtain the system thermal efficiencies from the hourly,daily and long-term performance tests.The thermal performance of the proposed system is compared with conventional solar water heaters.The results show that the proposed system achieves system characteristic efficiency of 10% higher than that of the conventional systems using electric pump if taking the consumption of electric power into account.And the former is a zero carbon system.
文摘The coupling-wave equations of photorefractive wave mixing processes including two-and four-wave mixing are expressed as an unified matrix equation in the undepleted pump approximation.The lossless general solution of the matrix equation is obtained.The previous formulas of five wave-mixing processes in the undepleted pump are derived from the solution when their boundary conditions are used.
文摘Reducing CO2 emissions and restraining dependence on nuclear power generation are serious concerns in the prevention of global warming since the Great East Japan Earthquake. To do so, it is necessary to use and expand natural renewable energy source such as solar energy and to promote energy conservation. However, in high-latitude regions, it is difficult to directly and effectively use solar power due to on insufficient amount of solar radiation. If steam can be generated from warm water at less than 373 K, it is possible to obtain steam by solar water heaters from weak solar radiation and industrial waste warm water without the consumption of any fossil fuels. In this study, the authors have been developing a system which generates steam over 423 K from warm water at less than 373 K using an adsorption heat pump with zeolite. Therefore, bench-scale equipment which generates steam continuously and the experimental results are mentioned.
文摘ASHP （air source heat pump） water heater is a renewable and energy efficient device used for sanitary hot water production. The system comprises of a storage tank and heat pump connected by pipes. These major units can either be compact as in the integrated model or split as in the retro-fit model. In this research, the analysis of energy losses was performed using SIRAC （the Southern African refrigeration and air conditioning） residential split type heat pump of 1.2 kW input power to retrofit a 200 liter high pressure kwikhot storage tank without hot water being drawn off for the entire monitoring period. Likewise to experimentally determine the losses DAS （data acquisition system） was designed and built to measure Ta （ambient temperature; RH-relative humidity）, RH, To （ASHP outlet water temperature）, Ti （ASHP inlet water temperature） and Vh. （volume of water heated by ASHP unit）.The results showed that the heat energy gain to compensate standby losses could range from 1.8 kWh to 2.1 kWh with the corresponding electrical energy used by ASHP water heater ranging from 0.55 kWh to 0.66 kWh. The standby losses depend primarily on the Vh, the Ta and the RH while the influence of （To - Ti） is secondary. The results can be of valuable interest to manufacturer of retrofit ASHP unit for hot water production when matching the electrical energy required to compensate for the standby losses.
文摘Design method for a mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Then, a semi-open impeller for the mini centrifugal pump with 55mm impeller diameter is adopted in this research to take simplicity and maintenance into consideration. Splitter blades are adopted in this research to improve the performance and internal flow condition of mini centrifugal pump having large blade outlet angle. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on the performance and internal flow condition of the mini centrifugal pump. A three dimensional steady numerical flow analysis is conducted to analyze rotor, volute efficiency and loss caused by a vortex. It is clarified from the experimental results that the performance of the mini centrifugal pump is improved by the effect of the splitter blades. Flow condition at outlet of the rotor becomes uniform and back flow regions are suppressed in the case with the splitter blades.Further, the volute efficiency increases and the vortex loss decreases. In the present paper, the performance of the mini centrifugal pump is shown and the flow condition is clarified with the results of the experiment and the numerical flow analysis. Furthermore, the performance analyses of the mini centrifugal pumps with and without the splitter blades are conducted.
