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Effects of radiation and heat source/sink on unsteady MHD boundary layer flow and heat transfer over

Krishnendu Bhattacharyya

《化学科学与工程前沿(英文)》 2011年 第5卷 第3期   页码 376-384 doi: 10.1007/s11705-011-1121-0

摘要: In this paper, an investigation is made to study the effects of radiation and heat source/sink on the unsteady boundary layer flow and heat transfer past a shrinking sheet with suction/injection. The flow is permeated by an externally applied magnetic field normal to the plane of flow. The self-similar equations corresponding to the velocity and temperature fields are obtained, and then solved numerically by finite difference method using quasilinearization technique. The study reveals that the momentum boundary layer thickness increases with increasing unsteadiness and decreases with magnetic field. The thermal boundary layer thickness decreases with Prandtl number, radiation parameter and heat sink parameter, but it increases with heat source parameter. Moreover, increasing unsteadiness, magnetic field strength, radiation and heat sink strength boost the heat transfer.

关键词: MHD boundary layer     unsteady flow     heat transfer     thermal radiation     heat source/sink     shrinking sheet     suction/injection    

Performance analysis of an air-source heat pump using an immersed water condenser

Jie JI, Huide FU, Hanfeng HE, Gang PEI,

《能源前沿(英文)》 2010年 第4卷 第2期   页码 234-245 doi: 10.1007/s11708-009-0056-3

摘要: A distributed model of an air-source heat pump (ASHP) system and its experimental setup using an immersed water condenser were presented. Dynamic performance of the ASHP was then evaluated by both simulation and experiment. The results indicated that the system coefficient of performance (COP) decreased as the condenser temperature increased, ranging from 4.41 to 2.32 with the average COP equaling 3.29 during the experiment. Comparisons between simulation results and experimental measurements demonstrated that the model was able to yield satisfactory predictions. Furthermore, temperature profiles of the refrigerant in the evaporator and condenser were also given. This paper provides the theoretical and experimental background for ASHP system optimization and a valuable reference for a solar air-source heat pump water heater when the solar irradiation energy is insufficient on cloudy or rainy days.

关键词: air-source     heat pump     distributed model     immersed water condenser    

Optimization model analysis of centralized groundwater source heat pump system in heating season

Shilei LU,Yunfang QI,Zhe CAI,Yiran LI

《能源前沿(英文)》 2015年 第9卷 第3期   页码 343-361 doi: 10.1007/s11708-015-0372-8

摘要: The ground-water heat-pump system (GWHP) provides a high efficient way for heating and cooling while consuming a little electrical energy. Due to the lack of scientific guidance for operating control strategy, the coefficient of performance (COP) of the system and units are still very low. In this paper, the running strategy of GWHP was studied. First, the groundwater thermal transfer calculation under slow heat transfixion and transient heat transfixion was established by calculating the heat transfer simulation software Flow Heat and using correction factor. Next, heating parameters were calculated based on the building heat load and the terminal equipment characteristic equation. Then, the energy consumption calculation model for units and pumps were established, based on which the optimization method and constraints were established. Finally, a field test on a GWHP system in Beijing was conducted and the model was applied. The new system operation optimization idea for taking every part of the GWHP into account that put forward in this paper has an important guiding significance to the actual operation of underground water source heat pump.

关键词: optimization model     groundwater source heat pump system     theoretical analysis     example verification     heating season    

Optimisation for interconnected energy hub system with combined ground source heat pump and borehole

Da HUO, Wei WEI, Simon Le BLOND

《能源前沿(英文)》 2018年 第12卷 第4期   页码 529-539 doi: 10.1007/s11708-018-0580-0

摘要: Ground source heat pumps (GSHP) give zero-carbon emission heating at a residential level. However, as the heat is discharged, the temperature of the ground drops, leading to a poorer efficiency. Borehole inter-seasonal thermal storage coupled with GSHP maintains the efficiency at a high level. To adequately utilize the high performance of combined GSHP and the borehole system to further increase system efficiency and reduce cost, such a combined heating system is incorporated into the interconnected multi-carrier system to support the heat load of a community. The borehole finite element (FE) model and an equivalent borehole transfer function are proposed and respectively applied to the optimisation to analyze the variation of GSHP performance over the entire optimisation time horizon of 24 h. The results validate the borehole transfer function, and the optimisation computation time is reduced by 17 times compared with the optimisation using the FE model.

关键词: borehole thermal storage     energy hub     ground source heat pumps (GSHP)     particle swarm optimisation    

pumping analysis and experimental validation of beach well infiltration intake system in a seawater sourceheat pump system

Huan ZHANG,Shu LIU,Xuejing ZHENG,Gaofeng CHEN

《能源前沿(英文)》 2015年 第9卷 第3期   页码 335-342 doi: 10.1007/s11708-015-0365-7

摘要: Based on energy conservation equation and Darcy’s law, a model of beach well infiltration intake system applied in a seawater source heat pump system was established. The model consists of the seawater seepage and the heat transfer process. A porous medium model in a software named FLUENT was applied to simulate the seepage and the heat transfer process. This model was also validated by field experiment conducted on the seashore in Tianjin, China. The maximum relative error between simulation results and experimental results was 2.1% (less than 5%), which was acceptable in engineering application. The porosity and coefficient of thermal conductivity of the aquifer soil were determined to be 0.49 W/(m·K) and 1.46 W/(m·K), respectively in the simulation. In addition, the influencing factors of pumping water of beach well were also analyzed. The pumping water was found to increase when the distance between the beach well and the impervious boundary becomes longer, when the distance between the beach well and the supplying water source shortens, when the diameter of the beach well enlarges, and the drawdown enlarges.

关键词: water pumping analysis     experimental validation     infiltration intake system     seawater source heat pump    

R&D of the ground-coupled heat pump technology in China

Nairen DIAO, Ping CUI, Junhong LIU, Zhaohong FANG,

《能源前沿(英文)》 2010年 第4卷 第1期   页码 47-54 doi: 10.1007/s11708-009-0080-3

摘要: The ground-coupled heat pump (GCHP) systems have been identified as one of the best sustainable energy technologies for space heating and cooling in residential and commercial buildings. In this paper, research on and development of the GCHP technology in China are summarized. New models are presented for efficient thermal analysis of ground heat exchangers, of which one- and two-dimensional solid cylindrical source models and their analytical solutions are devised to deal with pile ground heat exchangers. Analytical solutions are also derived for vertical and inclined finite line source models as well as for a groundwater advection model. Explicit solutions of a quasi-three-dimensional model can be used to better evaluate the thermal resistance inside boreholes. Studies on hybrid GCHP systems and the thermal response test in China are also commented.

关键词: ground source heat pump     ground heat exchanger     HVAC     China    

A two-stage deep freezing chemisorption cycle driven by low-temperature heat source

Yuanyang HU, Liwei WANG, Lu XU, Ruzhu WANG, Jeremiah KIPLAGAT, Jian WANG

《能源前沿(英文)》 2011年 第5卷 第3期   页码 263-269 doi: 10.1007/s11708-011-0152-z

摘要: A two-stage chemisorption cycle suitable for deep-freezing application driven by low- temperature heat source was proposed. Through two-stage desorption processes, the two-stage cycle can break through the limitations of the heating temperature and ambient cooling temperature. The two-stage cycle based on CaCl /BaCl -NH working pair can utilize the heat source with a temperature of above 75°C, and simultaneously realize deep-freezing all the year round. Experimental results and performance prediction show that the adsorption quantity of calcium, theoretical coefficient of performance (COP) and optimized specific cooling power (SCP) of the CaCl /BaCl -NH chemisorption system are 0.489 kg/kg (salt), 0.24 and 120.7 W/kg, when the heating temperature, ambient cooling temperature, pseudo-evaporating temperature and mass ratio of reacting salt and expanded graphite are 85, 30, -20, and 4∶1, respectively.

关键词: adsorption     freezing     desorption     heat source    

基于平板热管的新型直膨式辐射可调节供暖末端 Article

吴一凡, 孙弘历, 段梦凡, 林波荣, 赵恒昕, 刘兆鸿

《工程(英文)》 2023年 第20卷 第1期   页码 192-207 doi: 10.1016/j.eng.2021.09.019

摘要:

建筑供暖电气化是实现碳中和目标的有效途径。作为一种清洁和可持续的电气化供暖技术,空气源热泵被广泛应用于缺乏集中供暖的地区。然而,现有末端形式存在难以同时实现间歇性和舒适性,且作为主要构件尚未较好地与空气源热泵匹配等问题。因此,本研究提出了一种与空气源热泵结合的新型辐射可调节供暖末端,以实现电气化节能减碳、间歇性和更好的热舒适性。针对辐射供暖末端目前存在三个主要问题,分别是峰值供热量受限、可调节性受限以及难以与空气源热泵结合,本文通过改进末端结构设计(改进A~E)提供了有效解决方案。研究结果表明,新末端能够将峰值供热量提升23.6%,并为使用者提供从10.1%到30.9%的可调辐射比。在此基础上,巧妙地借助平板热管减少了原有直膨式辐射供暖末端的制冷剂管路长度,进而改善了供暖末端的稳定性(利于回油)、间歇性(降低热惯性)和安全性(降低制冷剂泄漏风险)。此外,本文基于新末端提出了一种新的分阶段运行策略,可进一步提升末端的可调节性。本研究可以为电气化供暖助力建筑低碳提供一定参考。

关键词: 新型供暖末端     空气源热泵     结构优化设计     峰值供热能力     快速可调节性     房间温度分布    

Finite element modeling of thermo-active diaphragm walls

Yi RUI, Mei YIN

《结构与土木工程前沿(英文)》 2020年 第14卷 第3期   页码 646-663 doi: 10.1007/s11709-020-0584-9

摘要: There are two major challenges faced by modern society: energy security, and lowering carbon dioxide gas emissions. Thermo-active diaphragm walls have a large potential to remedy one of these problems, since they are a renewable energy technology that uses underground infrastructure as a heat exchange medium. However, extensive research is required to determine the effects of cyclic heating and cooling on their geotechnical and structural performance. In this paper, a series of detailed finite element analyses are carried out to capture the fully coupled thermo-hydro-mechanical response of the ground and diaphragm wall. It is demonstrated that the thermal operation of the diaphragm wall causes changes in soil temperature, thermal expansion/shrinkage of pore water, and total stress applied on the diaphragm wall. These, in turn, cause displacements of the diaphragm wall and variations of the bending moments. However, these effects on the performance of diaphragm wall are not significant. The thermally induced bending strain is mainly governed by the temperature differential and uneven thermal expansion/shrinkage across the wall.

关键词: thermo-active diaphragm wall     finite element analysis     thermo-hydro-mechanical coupling     ground source heat pump    

Development of source profiles and their application in source apportionment of PM

Ningning Zhang, Mazhan Zhuang, Jie Tian, Pengshan Tian, Jieru Zhang, Qiyuan Wang, Yaqing Zhou, Rujin Huang, Chongshu Zhu, Xuemin Zhang, Junji Cao

《环境科学与工程前沿(英文)》 2016年 第10卷 第5期 doi: 10.1007/s11783-016-0879-1

摘要: Seasonal and spatial distribution of PM and its component were shown. Local source profiles of major PM sources were developed. Source apportionment was conducted using CMB model. Inorganic secondary components is the biggest contribution at Xiamen. Ambient PM samples were collected at four sites in Xiamen, including Gulangyu (GLY), Hongwen (HW), Huli (HL) and Jimei (JM) during January, April, July and October 2013. Local source samples were obtained from coal burning power plants, industries, motor vehicles, biomass burning, fugitive dust, and sea salt for the source apportionment studies. The highest value of PM mass concentration and species related to human activities (SO , NO , Pb, Ni, V, Cu, Cd, organic carbon (OC) and elemental carbon (EC)) were found in the ambient samples from HL, and the highest and lowest loadings of PM and its components occurred in winter and summer, respectively. The reconstructed mass balance indicated that ambient PM consisted of 24% OM (organic matter), 23% sulfate, 14% nitrate, 9% ammonium, 9% geological material, 6% sea salt, 5% EC and 10% others. For the source profiles, the dominant components were OC for coal burning, motor vehicle, biomass burning and sea salt; SO for industry; and crustal elements for fugitive dust. Source contributions were calculated using a chemical mass balance (CMB) model based on ambient PM concentrations and the source profiles. GLY was characterized by high contributions from secondary sulfate and cooking, while HL and JM were most strongly affected by motor vehicle emissions, and biomass burning and fugitive dust, respectively. The CMB results indicated that PM from Xiamen is composed of 27.4% secondary inorganic components, 20.8% motor vehicle emissions, 11.7% fugitive dust, 9.9% sea salt, 9.3% coal burning, 5.0% biomass burning, 3.1% industry and 6.8% others.

关键词: PM2.5     Source profile     Source apportionment     CMB     Xiamen    

Absorption heat pump for waste heat reuse: current states and future development

Zhenyuan XU, Ruzhu WANG

《能源前沿(英文)》 2017年 第11卷 第4期   页码 414-436 doi: 10.1007/s11708-017-0507-1

摘要: Absorption heat pump attracts increasing attention due to its advantages in low grade thermal energy utilization. It can be applied for waste heat reuse to save energy consumption, reduce environment pollution, and bring considerable economic benefit. In this paper, three important aspects for absorption heat pump for waste heat reuse are reviewed. In the first part, different absorption heat pump cycles are classified and introduced. Absorption heat pumps for heat amplification and absorption heat transformer for temperature upgrading are included. Both basic single effect cycles and advanced cycles for better performance are introduced. In the second part, different working pairs, including the water based working pairs, ammonia based working pairs, alcohol based working pairs, and halogenated hydrocarbon based working pairs, for absorption heat pump are classified based on the refrigerant. In the third part, the applications of the absorption heat pump and absorption heat transformer for waste heat reuse in different industries are introduced. Based on the reviews in the three aspects, essential summary and future perspective are presented at last.

关键词: absorption     heat pump     heat transformer     waste heat     working pair    

The source and transport of bioaerosols in the air: A review

《环境科学与工程前沿(英文)》 2021年 第15卷 第3期 doi: 10.1007/s11783-020-1336-8

摘要:

• Emission of microbe from local environments is a main source of bioaerosols.

关键词: Bioaerosols     Diffusion     Source identification     Biogeography    

δN-stable isotope analysis of NH: An overview on analytical measurements, source sampling and its source

《环境科学与工程前沿(英文)》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1414-6

摘要:

• Challenges in sampling of NH3 sources for d15N analysis are highlighted.

关键词: Aerosol ammonium     Atmospheric gaseous ammonia     Isotope fingerprinting     Isotope-based source apportionment     Ammonia gas-to-particle conversion    

Fault tolerant control strategy for modular PWM current source inverter

《能源前沿(英文)》 2023年 第17卷 第2期   页码 228-238 doi: 10.1007/s11708-022-0852-6

摘要: In this paper, a fault-tolerant control method for an input-series output-parallel modular grid-tied pulse-width modulation (PWM) current source inverter is proposed to address the most commonly seen single symmetrical gate-commutated thyristor (SGCT) open-circuit fault problems. This method actively offsets the neutral point of the current space vector to ensure a sinusoidal output of the grid current, and it can achieve the upper limit power of the inverter under the condition of a single SGCT open-circuit fault. In addition, an active damping control method based on grid harmonic current feedback is proposed after analyzing the influence of the transformer ferromagnetic resonance caused by the neutral point offset on the power quality of the grid current. It has been demonstrated that the proposed method effectively suppresses the resonance caused by the transformer and the modified modulation, improving the grid current’s power quality.

关键词: current source converter (CSC)     fault-tolerant control     space vector modulation     active damping     resonance suppression     power quality    

Heat-spreading analysis of a heat sink base embedded with a heat pipe

B. V. BORGMEYER, H. B. MA,

《能源前沿(英文)》 2010年 第4卷 第2期   页码 143-148 doi: 10.1007/s11708-010-0013-1

摘要: A simplified model predicting the heat transfer performance of a heat sink base with a high thermal conductivity was developed. Numerical analysis was performed using the commercial software FLUENT. The investigation indicates that for heat sink bases with a high effective thermal conductivity, such as the base embedded with a typical heat pipe, the entire heat sink can be modeled as a flat plate with a uniform temperature and an effective convection heat transfer coefficient. This simplified model can be used to determine the heat transfer performance of a heat sink embedded with a typical heat pipe or vapor chamber.

关键词: heat pipe     heat sink     microprocessor heat removal    

标题 作者 时间 类型 操作

Effects of radiation and heat source/sink on unsteady MHD boundary layer flow and heat transfer over

Krishnendu Bhattacharyya

期刊论文

Performance analysis of an air-source heat pump using an immersed water condenser

Jie JI, Huide FU, Hanfeng HE, Gang PEI,

期刊论文

Optimization model analysis of centralized groundwater source heat pump system in heating season

Shilei LU,Yunfang QI,Zhe CAI,Yiran LI

期刊论文

Optimisation for interconnected energy hub system with combined ground source heat pump and borehole

Da HUO, Wei WEI, Simon Le BLOND

期刊论文

pumping analysis and experimental validation of beach well infiltration intake system in a seawater sourceheat pump system

Huan ZHANG,Shu LIU,Xuejing ZHENG,Gaofeng CHEN

期刊论文

R&D of the ground-coupled heat pump technology in China

Nairen DIAO, Ping CUI, Junhong LIU, Zhaohong FANG,

期刊论文

A two-stage deep freezing chemisorption cycle driven by low-temperature heat source

Yuanyang HU, Liwei WANG, Lu XU, Ruzhu WANG, Jeremiah KIPLAGAT, Jian WANG

期刊论文

基于平板热管的新型直膨式辐射可调节供暖末端

吴一凡, 孙弘历, 段梦凡, 林波荣, 赵恒昕, 刘兆鸿

期刊论文

Finite element modeling of thermo-active diaphragm walls

Yi RUI, Mei YIN

期刊论文

Development of source profiles and their application in source apportionment of PM

Ningning Zhang, Mazhan Zhuang, Jie Tian, Pengshan Tian, Jieru Zhang, Qiyuan Wang, Yaqing Zhou, Rujin Huang, Chongshu Zhu, Xuemin Zhang, Junji Cao

期刊论文

Absorption heat pump for waste heat reuse: current states and future development

Zhenyuan XU, Ruzhu WANG

期刊论文

The source and transport of bioaerosols in the air: A review

期刊论文

δN-stable isotope analysis of NH: An overview on analytical measurements, source sampling and its source

期刊论文

Fault tolerant control strategy for modular PWM current source inverter

期刊论文

Heat-spreading analysis of a heat sink base embedded with a heat pipe

B. V. BORGMEYER, H. B. MA,

期刊论文