scholarly journals Theoretical analysis and experimental research of heat pump driving heat pipes heating equipment

2020 ◽  
Vol 24 (2 Part A) ◽  
pp. 1019-1029
Author(s):  
Ruochen Ding ◽  
Baorui Du ◽  
Shuxue Xu ◽  
Jun Yao ◽  
Huilong Zheng
Keyword(s):  
Heat Pipe ◽  
Heat Pump ◽  
Composite System ◽  
Working Condition ◽  
Heat Pipes ◽  
Design Parameters ◽  
Heating Equipment ◽  
Start Up ◽  
Heating Capacity ◽  
Operation Characteristics

In this study, the main design parameters of the heat pump/heat pipe composite system were calculated. The operation characteristics of the heat pump/heat pipe composite system under low temperature were experimentally studied. The start-up character of the heat pipe radiator and heat pipe radiator surface temperature distribution were obtained. The variation of heating capacity and heating coefficient of performaance of the heat pump/heat pipe composite system with different working condition was obtained. Experimental results show that the heat pump/heat pipe composite system can operate efficiently and steadily when the outdoor temperature is ?20~5?C, and meet the winter heating demand in cold areas.

scholarly journals Energy Benefits of Heat Pipe Technology for Achieving 100% Renewable Heating and Cooling for Fifth-Generation, Low-Temperature District Heating Systems

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5398
Author(s):  
Birol Kılkış ◽  
Malik Çağlar ◽  
Mert Şengül
Keyword(s):  
Low Temperature ◽  
Heat Pipe ◽  
Co2 Emissions ◽  
Low Temperatures ◽  
Heat Pipes ◽  
Paris Agreement ◽  
Heating Equipment ◽  
Heating Systems ◽  
Heating And Cooling ◽  
The Eu

This paper addresses the challenges the policymakers face concerning the EU decarbonization and total electrification roadmaps towards the Paris Agreement set forth to solve the global warming problem within the framework of a 100% renewable heating and cooling target. A new holistic model was developed based on the Rational Exergy Management Model (REMM). This model optimally solves the energy and exergy conflicts between the benefits of using widely available, low-temperature, low-exergy waste and renewable energy sources, like solar energy, and the inability of existing heating equipment, which requires higher exergy to cope with such low temperatures. In recognition of the challenges of retrofitting existing buildings in the EU stock, most of which are more than fifty years old, this study has developed a multi-pronged solution set. The first prong is the development of heating and cooling equipment with heat pipes that may be customized for supply temperatures as low as 35 °C in heating and as high as 17 °C in cooling, by which equipment oversizing is kept minimal, compared to standard equipment like conventional radiators or fan coils. It is shown that circulating pump capacity requirements are also minimized, leading to an overall reduction of CO2 emissions responsibility in terms of both direct, avoidable, and embodied terms. In this respect, a new heat pipe radiator prototype is presented, performance analyses are given, and the results are compared with a standard radiator. Comparative results show that such a new heat pipe radiator may be less than half of the weight of the conventional radiator, which needs to be oversized three times more to operate at 35 °C below the rated capacity. The application of heat pipes in renewable energy systems with the highest energy efficiency and exergy rationality establishes the second prong of the paper. A next-generation solar photo-voltaic-thermal (PVT) panel design is aimed to maximize the solar exergy utilization and minimize the exergy destruction taking place between the heating equipment. This solar panel design has an optimum power to heat ratio at low temperatures, perfectly fitting the heat pipe radiator demand. This design eliminates the onboard circulation pump, includes a phase-changing material (PCM) layer and thermoelectric generator (TEG) units for additional power generation, all sandwiched in a single panel. As a third prong, the paper introduces an optimum district sizing algorithm for minimum CO2 emissions responsibility for low-temperature heating systems by minimizing the exergy destructions. A solar prosumer house example is given addressing the three prongs with a heat pipe radiator system, next-generation solar PVT panels on the roof, and heat piped on-site thermal energy storage (TES). Results showed that total CO2 emissions responsibility is reduced by 96.8%. The results are discussed, aiming at recommendations, especially directed to policymakers, to satisfy the Paris Agreement.

Analysis of Heat Pipe Filled with Several Oxide Nanofluids on the Start-Up Process

2014 ◽  
Vol 490-491 ◽  
pp. 251-255 ◽  
Author(s):  
Yu Ying Gong ◽  
Zong Ming Liu ◽  
Wei Lin Zhao
Keyword(s):  
Temperature Distribution ◽  
Heat Pipe ◽  
Temperature Drop ◽  
Heat Pipes ◽  
Condenser Section ◽  
Evaporator Section ◽  
Heating Section ◽  
Start Up

Three heat pipes with nanofluids of Al2O3-water, CuO-water and SiO2-water were tested experimentally. The temperature distribution of their start-up process was analysed, and compared the heat pipe with water. The results showed that the start-up way of heat pipe filled with nanofluids was coincident, the heat pipe filled with nanofluids showed a lower start-up temperature and a shorter start-up time in evaporator section compared with heat pipe filled with water, the temperature drop between evaporator section and condenser section for the heat pipe filled with nanofluids were reduced by 2-5°C than that of the heat pipe filled with water. The effect of the length of the heating section of heat pipe filled with nanofluids on the start-up process was little.

Fundamental Heat Transfer Experiments of Heat Pipes for Turbine Cooling

1998 ◽  
Vol 120 (3) ◽  
pp. 580-587 ◽  
Author(s):  
S. Yamawaki ◽  
T. Yoshida ◽  
M. Taki ◽  
F. Mimura
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Cooling System ◽  
Infrared Image ◽  
Heat Pipes ◽  
Performance Criteria ◽  
Working Fluid ◽  
Steel Shell ◽  
Turbine Cooling ◽  
Start Up

Fundamental heat transfer experiments were carried out for three kinds of heat pipes that may be applied to turbine cooling in future aero-engines. In the turbine cooling system with a heat pipe, heat transfer rate and start-up time of the heat pipe are the most important performance criteria to evaluate and compare with conventional cooling methods. Three heat pipes are considered, called heat pipe A, B, and C, respectively. All heat pipes have a stainless steel shell and nickel sintered powder metal wick. Sodium (Na) was the working fluid for heat pipes A and B; heat pipe C used eutectic sodium-potassium (NaK). Heat pipes B and C included noncondensible gas for rapid start-up. There were fins on the cooling section of heat pipes. In the experiments, and infrared image furnace supplied heat to the heat pipe simulating turbine blade surface conditions. In the results, heat pipe B demonstrated the highest heat flux of 17 to 20 W/cm2. The start-up time was about 6 minutes for heat pipe B and about 16 minutes for heat pipe A. Thus, adding noncondensible gas effectively reduced start-up time. Although NaK is a liquid phase at room temperature, the startup time of heat pipe C (about 7 to 8 minutes) was not shorter than the heat pipe B. The effect of a gravitational force on heat pipe performance was also estimated by inclining the heat pipe at an angle of 90 deg. There was no significant gravitational dependence on heat transport for heat pipes including noncondensible gas.

Experimental Model to Optimize the Design of Cylindrical Heat Pipes for Solar Collector Application

2013 ◽  
Vol 393 ◽  
pp. 735-740
Author(s):  
Fairosidi Idrus ◽  
Nazri Mohamad ◽  
Ramlan Zailani ◽  
Wisnoe Wirachman ◽  
Mohd Zulkifly Abdullah
Keyword(s):  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Pipes ◽  
Design Parameters ◽  
Working Fluid ◽  
Pipe Material ◽  
Efficient Design ◽  
Wick Structure ◽  
To Come ◽  
Transfer Device

A heat pipe is a heat-transfer device that use the principles of thermal conductivity and phase change to transfer heat between two ends at almost constant temperature. The thermal peformance of cylindrical heat pipes depends on design parameters such as dimensions of the heat pipe, material, wick structure and the working fluid. An experimental strategy was designed to study the effect of these parameters on the thermal performance of cylindrical heat pipes. The experimental design was conceived by employing the Taguchi method. The final aim of the experiments is to come up with design parameters that will yield optimum thermal performance. This paper presents an efficient design of experiment and the associated experimental setup and procedures to be carried out in order to optimize the design of cylindrical heat pipes.

scholarly journals Fundamental Heat Transfer Experiments of Heat Pipes for Turbine Cooling

1997 ◽  
Author(s):  
Shigemichi Yamawaki ◽  
Toyoaki Yoshida ◽  
Masanobu Taki ◽  
Fujio Mimura
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Cooling System ◽  
Infrared Image ◽  
Heat Pipes ◽  
Performance Criteria ◽  
Working Fluid ◽  
Steel Shell ◽  
Turbine Cooling ◽  
Start Up

Fundamental heat transfer experiments were carried out for three kinds of heat pipes which may be applied to turbine cooling in future aero-engines. In the turbine cooling system with a heat pipe, heat transfer rate and start-up time of the heat pipe are the most important performance criteria to evaluate and compare with conventional cooling methods. Three heat pipes are considered, called heat pipe A, B and C, respectively. All heat pipes have a stainless steel shell and nickel sintered powder metal wick. Sodium(Na) was the working fluid for heat pipes A and B; heat pipe C used eutectic sodium-potassium(NaK). Heat pipes B and C included non-condensible gas for rapid start-up. There were fins on the cooling section of heat pipes. In the experiments, an infrared image furnace supplied heat to the heat pipe simulating turbine blade surface conditions. In the results, heat pipe B demonstrated the highest heat flux of 17 to 20 W/cm2. The start-up time was about 6 minutes for heat pipe B and about 16 minutes for heat pipe A. Thus adding non-condensible gas effectively reduced start-up time. Although NaK is a liquid phase at room temperature, the start-up time of heat pipe C (about 7 to 8 minutes) was not shorter than the heat pipe B. The effect of a gravitational force on heat pipe performance was also estimated by inclining the heat pipe at an angle of 90 degrees. There was no significant gravitational dependence on heat transport for heat pipes including non-condensible gas.

scholarly journals Thermal Performances Investigation of Anti-Gravity Heat Pipe with Tapering Phase-Change Chamber

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5036
Author(s):  
Jianhua Xiang ◽  
Xi-bo Chen ◽  
Jiale Huang ◽  
Chunliang Zhang ◽  
Chao Zhou ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Heat Pipe ◽  
Heat Pipes ◽  
Cross Sectional ◽  
Start Up ◽  
Transfer Capability ◽  
Frequent Switching ◽  
Wick Structure ◽  
Better Than

The objective of this study was to fabricate anti-gravity heat pipes with a tapering column phase-change chamber and changeable cross-sectional wick structure. The thermal performances of the anti-gravity heat pipes were experimentally investigated. Results show that the thermal resistances of the different heat pipes are less than 0.03 °C/W, except for the sharp conical chamber heat pipe under anti-gravity heating conditions (0.121 °C/W). Start-up times of different types of heat pipes are similar and the temperatures are steady within 3 to 5 min. The heat transfer ability of a conical chamber is always better than that of a cylindrical one. The performance of the sharp conical chamber heat pipe is the best under gravity assistance heating conditions. Contrarily, the blunt conical chamber heat pipe has the best heat transfer ability under anti-gravity heating conditions. Moreover, the heat transfer capability of the blunt conical chamber heat pipe is unaffected by the relative position of the heat and cold sources, which is suitable for constant temperature cooling applications with frequent switching of the heat and cold sources.

Experimental Study on Heat Transfer Characteristic of Plate Pulsating Heat Pipe

2009 ◽  
Author(s):  
Li Quan ◽  
Li Jia
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Cross Section ◽  
Heat Pipes ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Pulsating Heat Pipe ◽  
Operating Characteristics ◽  
Cross Sectional ◽  
Start Up

An experimental system of flat plate pulsating heat pipe was established and experimental research was carried out in this system to understand the mechanism of heat transfer and operating characteristics. The effects of start-up time, operating characteristics, and structures of passage, incline angle, fill ratio and working fluid on plate pulsating heat pipe were discussed. The results indicate that temperature of heating section decreases and the temperature of cooling section increases, then the thermal resistant of PHP is decreased once the plate pulsating heat pipe starts to work. Different start-up powers are needed for different fill ratios and incline angles. The inter pressure of PHP has some impacts on the start-up and operation of PHP. The pulsating heat pipes with different structures have different heat transfer performance. Increasing cross-sectional area and the number of turnings of the heat pipe can improve the heat transfer characteristics of heat pipes. Cross-section shape was also an important influencing factor. With the same cross-sectional area, heat pipe with triangular cross-section of the inner tubes gives better performance than that with rectangular cross-section.

Study on Analogue Simulation of the Influences of Thermal Parameters on the Performance of Water Source Heat Pump under Variable Working Condition

2011 ◽  
Vol 71-78 ◽  
pp. 3789-3793
Author(s):  
Shi Lin Qu ◽  
Han Qing Luo
Keyword(s):  
Mathematical Models ◽  
Heat Pump ◽  
Virtual Instrument ◽  
Working Condition ◽  
Water Source ◽  
Thermal Parameters ◽  
Analogue Simulation ◽  
Heating Capacity ◽  
And Control ◽  
Lower Heating

Taking thermal parameters such as evaporating temperature, condensing temperature, superheating temperature and sub-cooled temperature as the basic variables and serving COP and heating capacity as evaluating indicators, this paper builds a series of mathematical models according to the rationale of WSHP and the correlation of its components and a simulation platform based on Laboratory Virtual Instrument Engineering Workbench (LabVIEW), simulates and analyzes the influence of thermal parameters on the performance of WSHP under variable working condition. The results show that evaporating temperature and condensing temperature have more significant effect on the performance of WSHP than both of superheating temperature and sub-cooled temperature and lower condensing temperature and higher evaporating temperature can raise the value of COP but reduce heating capacity. They also show that lower superheating temperature will bring higher value of COP but lower heating capacity and higher sub-cooled temperature can make both COP value and heating capacity increase. On the simulative condition, the influence rates of evaporating temperature, condensing temperature, superheating temperature and sub-cooled temperature relative to COP of WSHP respectively are 2.25%，2.61%，0.7% and 0.51% and the influence rates of these temperatures relative to heating capacity respectively are 1.32%，1.09%，0.58% and 0.77%. These results may provide with some reliable foundations on optimizing operation and control of WSHP under variable working condition.

scholarly journals Experimental Research on the Thermal Performance and Semi-Visualization of Rectangular Flat Micro-Grooved Gravity Heat Pipes

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2480
Author(s):  
Xiang Gou ◽  
Qiyan Zhang ◽  
Yamei Li ◽  
Yingfan Liu ◽  
Shian Liu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Pipes ◽  
Bipolar Transistors ◽  
Load Range ◽  
Equivalent Thermal Conductivity ◽  
Start Up ◽  
Phase Behaviors

To strengthen the heat dissipating capacity of a heat pipe used for integrated insulated gate bipolar transistors, as an extension of our earlier work, the effect of micro-groove dimension on the thermal performance of flat micro-grooved gravity heat pipe was studied. Nine pipes with different depths (0.4 mm, 0.8 mm, 1.2 mm) and widths (0.4 mm, 0.8 mm, 1.2 mm) were fabricated and tested under a heating load range from 80 W to 180 W. The start-up time, temperature difference, relative thermal resistance and equivalent thermal conductivity were presented as performance indicators by comparison of flat gravity heat pipes with and without micro-grooves. Results reveal that the highest equivalent thermal conductivity of the flat micro-grooved gravity heat pipes is 2.55 times as that of the flat gravity heat pipe without micro-grooves. The flat gravity heat pipes with deeper and narrower micro-grooves show better thermal performance and the optimal rectangular micro-groove dimension among the selected options is determined to be 1.2 mm (depth) × 0.4 mm (width). Furthermore, the liquid–vapor phase behaviors were observed to verify the heat transfer effects and analyze the heat transfer mechanism of the flat micro-grooved heat pipes.

scholarly journals Study on the Adaptability of Extracting Steam and Heat Return Pipe System of Heating Unit

2021 ◽  
Vol 11 (2) ◽  
pp. 71
Author(s):  
Liming Zhai ◽  
Yaosen Chen ◽  
Zhiwei Li ◽  
Xiaochen Chen ◽  
Jiongming Wang ◽  
...  
Keyword(s):  
Heat Pipe ◽  
Heating System ◽  
Scientific Basis ◽  
Design Parameters ◽  
Actual Situation ◽  
Heating Unit ◽  
Flow Rates ◽  
Pipe System ◽  
Heating Capacity ◽  
Before And After

In view of the insufficient heating capacity of a supercritical 600 WM unit, it is necessary to determine whether the equipment of the extraction and return heat pipe system can operate normally after the transformation, so as to check the adaptability of the extraction and return heat pipe system equipment of the heating unit. Based on the actual situation and heat balance before and after the transformation of the heating system, this study selects the extracting steam and heat return pipe system of the heating units at all levels, and makes adaptive accounting from the design parameters of the pipeline, and the calculations of steam flow rates or pipe diameters of the pipeline, which provide scientific basis and evaluation for the feasibility of the retrofit scheme.

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