Numerical Calculation on Heat Transfer Performance of the Capillary Plane HVAC Terminal System

2008 ◽  
Author(s):  
Wei Bing ◽  
Li Li ◽  
Shuping Zhang ◽  
Jiang Lu
Keyword(s):  
Heat Transfer ◽  
Numerical Calculation ◽  
Indoor Air ◽  
Heat Transfer Performance ◽  
Influence Factors ◽  
Heating System ◽  
Flow Density ◽  
Transfer Performance ◽  
Terminal System ◽  
Average Temperature

Nowadays as a novel terminal air conditioning system, the capillary plane HVAC terminal system is being researched in China. In this system the terminal capillary pipes are buried in the surface of the ceiling or the wall or the floor with the purpose-built grout, the chilled or heated water circulates in the pipes and exchanges the sensible heat with the indoor air by radiation and convection to make the indoor air parameters stable. The capillary mat terminals usually combine with dedicated outdoor air system and the latter takes on the indoor latent heat. Compared with the floor radiant heating system, the capillary plane HVAC terminal system has the advantages of saving more indoor space and any position installation. In this paper, with the method of numerical calculation the heat transfer performance of the capillary pipe buried in the grout are studied, the average temperature of the radiation surface and average heat flow density in summer and winter are figured out, and the influence factors such as: the pipe spacing, pipe embedded depth, pipe diameter, average temperature of the supply and return water, and design indoor air temperature are analyzed respectively. The optimal mode or trend under given conditions are proposed and the relations of the influence factors are summarized. All these above will be good theoretical references for the design and application of the capillary plane HVAC terminal system.

Thermo-Fluid Dynamic Design Exploration of a Double Pipe Heat Exchanger

2019 ◽  
Author(s):  
Tomohiro Hirano ◽  
Mitsuo Yoshimura ◽  
Koji Shimoyama ◽  
Atsuki Komiya
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Nsga Ii ◽  
Cross Sectional ◽  
Average Temperature ◽  
Double Pipe ◽  
Sectional Shape ◽  
Pipe Heat

Abstract Toward a practical application of the additive manufacturing (AM), this study proposes a shape optimization approach for the cross-sectional shape of the inner pipe of a counter-flow double pipe heat exchanger. The cross-sectional shape of the inner pipe is expressed by an algebraic expression with a small number of parameters, and their heat transfer performance is evaluated by a commercial Computational Fluid Dynamics (CFD) solver. The optimization is conducted by the Non-Dominated Sorting Genetic Algorithm II (NSGA-II) assisted by the Kriging surrogate model, and the NSGA-II finds the optimal cross-sectional shape with many protrusions around the perimeter of the inner channel to improve the heat transfer performance. In this study, heat transfer performance is evaluated from the temperature drop at the outlet of the high-temperature fluid. Through the comparison of two cross-sectional shapes with the same heat transfer surface area — average temperature at the outlet of the optimal high-temperature channel is 324.58 K while average temperature at the outlet of a circular high-temperature channel with the same area as the optimal channel is 331.93 K, it is revealed that the number of protrusions plays important roles which contribute not only to increase heat transfer area but also to improve heat transfer performance.

scholarly journals Numerical study on heat transfer and flow resistance characteristics of multi-head twisted spiral tube

2021 ◽  
pp. 206-206
Author(s):  
Zhiqun Zheng ◽  
Fayi Yan ◽  
Lei Shi
Keyword(s):  
Heat Transfer ◽  
Numerical Calculation ◽  
Cross Section ◽  
Heat Transfer Performance ◽  
Numerical Study ◽  
Smooth Tube ◽  
Transfer Performance ◽  
Spiral Tube ◽  
Inside Diameter ◽  
The Cross

A numerical calculation model of multihead twisted spiral tube (MTST) was established. In the range of Reynolds number from 5000 to 35000, the influence of different twisted structure on the flow and heat transfer characteristics of the MTST was studied by numerical calculation. Numerical calculation results indicate that the Nusselt number and friction coefficient increase with the increase in the ratio of outside and inside diameter of the cross-section, the increase in the number of twisted nodes, and the increase in the number of twisted spiral tube heads. Under the condition of the same spiral structure and the same hydraulic diameter, the heat transfer performance of the MTST is better than that of the spiral smooth tube. In addition, through artificial neural network (ANN) analysis, the ratio of outside and inside diameter of the cross-section, number of twisted nodes, and the number of twisted spiral tube heads were optimized to promote the comprehensive heat transfer performance. The performance evaluation criterion is the highest when the ratio of outside and inside diameter of the cross-section is 25/22.5, the number of twisted nodes is 3, and the number of twisted spiral tube heads is 3, which is 1.849 of the spiral smooth tube.

Influence of Drainage and Tilt on Heat Transfer Performance of Array Pulsating Cold End Heat Pipe

2021 ◽  
pp. 1-8
Author(s):  
Guowei Xiahou ◽  
Hao Liu ◽  
Shun Zhang ◽  
Yecong He
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Average Temperature ◽  
New Type ◽  
The Difference ◽  
Drainage Effect ◽  
Better Than ◽  
Capillary Drainage

Abstract A new type of array pulsating cold section heat pipe was proposed, which consists of a T-shaped hot section and an array pulsating cold section. The special structure is available to drain the hot section of the heat pipe, and the installation method of the cold section has an important influence on heat transfer. For this reason, a detailed experimental study of heat transfer performance was carried out in this paper. It was found in the study that a capillary lifting force exists at the outlet of the cold section channel, which prevents the condensate from returning to the hot section, therefore, the hot section has to be drained; the drainage methods are divided into hot-section liquid drainage and hot-section capillary drainage, the latter is significantly better than the former; appropriate increase of the filling rate can improve the drainage effect of liquid drainage. The new heat pipe can adopt two methods, i.e., inclined cold section and vertical cold section. The reflux and heat transfer performance of the inclined cold section outperforms that of the vertical cold section, but the difference between the two methods gradually decreases with the increase of power. Under the same working conditions, the average temperature of the heat source of the new stainless steel heat pipe with the capillary drainage vertical cold section is lower than that of the aluminum fin radiator by 5.79%-10.78%, and the decreasing amplitude increases with the increase of the heating power.

THE INFLUENCE FACTORS ON HEAT TRANSFER PERFORMANCE OF LOOP THERMOSYPHON SYSTEM

2016 ◽  
Vol 40 (5) ◽  
pp. 947-958 ◽  
Author(s):  
Li-Chieh Hsu ◽  
Guo-Wei Wong ◽  
Kung-Ting Chen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Influence Factors ◽  
Passive Cooling ◽  
Width Ratio ◽  
Transfer Performance ◽  
Cooling Device ◽  
Cooling Performance ◽  
System A ◽  
Enhanced Boiling

The influence factors on the heat transfer performance of a loop thermosyphon system, a passive cooling device, are studied systematically. The parameters investigated include types of enhanced boiling structure, the depth to width ratio of enhanced boiling structures, the gap of evaporator, the condenser height and the inclination of evaporator. The results show the depth to width ratio and the condenser height has positive influences on the heat transfer performance. An optimal channel gap of evaporator exists and possesses better heat transfer performance. The inclination effect of evaporator may not be favorable to heat transfer. Among those, the horizontal and 90° inclination of evaporator has better cooling performance.

Study on Optimization of Evaporative Condenser Nozzle with CFD Method

2013 ◽  
Vol 275-277 ◽  
pp. 654-658
Author(s):  
Yue Zhao ◽  
Hong Jian Zhou ◽  
Jing Xie ◽  
Yi Tang ◽  
Chen Miao
Keyword(s):  
Heat Transfer ◽  
Numerical Calculation ◽  
Heat Transfer Performance ◽  
Optimal Structure ◽  
Transfer Performance ◽  
Two Dimensional ◽  
Dimensional Modeling ◽  
Operation Process ◽  
Cfd Method ◽  
Calculation Software

In the evaporative condenser, the shape and structure of the nozzle determines the spraying effect, which affects the overall heat transfer performance of the evaporative condenser. Due to the constraints of its structure, spraying test is difficult in evaporative condenser operation process. The performance of the two types of nozzle spray is simulated by CFD numerical calculation software, using the two-dimensional modeling. The results show that the two-tier shunt platform nozzle sprays more uniformly, the movement of airflow around is relative more regular, the performance of spraying water is more stable. The reference is provided to select the optimal structure of the nozzle under certain conditions.

scholarly journals Microchannel Liquid-Cooled Heat Exchanger Based on a Nonuniform Lattice: Study on Structure Calculation, Formation Process, and Boiling Heat Transfer Performance

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7248
Author(s):  
Bo Qian ◽  
Hongri Fan ◽  
Gang Liu ◽  
Jianrui Zhang ◽  
Pei Li
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Heat Flux Density ◽  
Heat Transfer Performance ◽  
Lattice Structure ◽  
Flow Density ◽  
Transfer Performance ◽  
Heat Flow Density ◽  
Uniform Frames

A microchannel radiator is advantageous due to its high efficiency and large boiling heat transfer coefficient of two-phase flow. Based on the research of uniform lattice structures, this study proposed a microchannel heat exchanger with a nonuniform lattice structure. The calculation, optimal formation, and boiling heat transfer performance of the nonuniform lattice structure based on selective laser melting (SLM) were investigated, and heat exchange samples were successfully prepared using SLM. The porosity and pore morphology of the samples were analysed, and the contrast experiments of boiling heat transfer were conducted with deionised water. The results revealed that the heat flow density of the lattice structure was a minimum of 244% higher than that of the traditional liquid-cooled plate. The critical heat flux density of the lattice structure is 110 W∙cm−2, and the critical heat flux density of the traditional flat plate is 45 W∙cm−2. In addition, the effects of cell structures indicated that for frame cells, the heat transfer effect of nonuniform frames was inferior to that of uniform frames; for face-centred cubic (FCC) cells, the nonuniform and uniform frames exhibited the same trend. However, the heat flow density of FCC cells was 25% higher than that of frame structures.

Sign in / Sign up

Export Citation Format

Share Document