Study on the Effect of the Evaporator Area on the Heat Transfer Performance in the Gravity Feed Liquid Refrigeration System

2013 ◽  
Vol 441 ◽  
pp. 112-115 ◽  
Author(s):  
Qing Jiang Liu ◽  
Fang Han
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Temperature Difference ◽  
Heat Transfer Performance ◽  
System Optimization ◽  
Transfer Performance ◽  
Refrigeration System ◽  
Original Design ◽  
The Heat Transfer Coefficient

In order to study the effect on heat transfer performance of evaporator in the gravity feed liquid refrigeration system the different evaporator area, the simulation procedure is worked out. The procedure uses the visual basic language. The procedure can figure out the heat transfer coefficient and the temperature difference in different evaporator area and evaporating temperature with the required refrigerating capacity. Through simulation calculation, when the area is 80% of the original design area of evaporator, the evaporator of the heat transfer coefficient and heat transfer temperature difference is the most reasonable and the evaporator of the refrigerating capacity can meet the requirements of cold storage. The program provides the reliable data for the gravity feed liquid cooling system optimization.

Enhancement of Heat Transfer Performance Using Ultrasonic Evaporation

2019 ◽  
Vol 15 (5-6) ◽  
Author(s):  
Jitian Song ◽  
Yongxia Feng ◽  
Wei Tian ◽  
Jianbo Liu ◽  
Yening Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Temperature Difference ◽  
Heat Transfer Performance ◽  
Tap Water ◽  
Ultrasonic Power ◽  
Transfer Performance ◽  
Ultrasonic Technology ◽  
The Heat Transfer Coefficient

AbstractThe ultrasonic evaporator is a new type of evaporation equipment which uses ultrasonic technology to assist evaporation of liquid materials. Due to the lack of mechanism of ultrasonic technology to enhance the heat transfer in evaporation process, there are few reports on the use of ultrasonic evaporator in industrial production. The tap water was selected as experimental material and the heat transfer performance of ultrasonic evaporator was studied. It could be obtained from the single factor analysis that the heat transfer coefficient increased first and then decreased with the increase of ultrasonic power density. The increase of heat transfer due to the increase of temperature difference is basically stable at 20 %. When the ultrasonic wave acts on evaporator, the heat transfer coefficient would increase about 17.06 %–29.85 %. According to the orthogonal test and analysis of variance, it can be obtained that the influence of temperature difference on heat transfer coefficient is the largest, the second is feed flow rate, and evaporation time has the least influence.

scholarly journals Experimental and Simulation Study of Micro-Channel Backplane Heat Pipe Air Conditioning System in Data Center

2020 ◽  
Vol 10 (4) ◽  
pp. 1255
Author(s):  
Liping Zeng ◽  
Xing Liu ◽  
Quan Zhang ◽  
Jun Yi ◽  
Xiaohua Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Outlet Temperature ◽  
Transfer Performance ◽  
Micro Channel ◽  
Heat Transfer Capacity ◽  
The Heat Transfer Coefficient

This paper mainly studies the heat transfer performance of backplane micro-channel heat pipes by establishing a steady-state numerical model. Compared with the experimental data, the heat transfer characteristics under different structure parameters and operating parameters were studied, and the change of heat transfer coefficient inside the system, the air outlet temperature of the back plate and the influence of different environmental factors on the heat transfer performance of the system were analyzed. The results show that the overall error between simulation results and experimental data is less than 10%. In the range of the optimal filling rate (FR = 64.40%–73.60%), the outlet temperature at the lowest point and the highest point of the evaporation section is 22.46 °C and 19.60 °C, the temperature difference does not exceed 3 °C, and the distribution gradient in vertical height is small and the air outlet temperature is uniform. The heat transfer coefficient between the evaporator and the condenser is larger than the heat transfer coefficient under the conditions of low and high liquid charge rate. It increases gradually along the flow direction, and decreases gradually with the flow rate of the condenser. When the width of the flat tube of the evaporator increases from 20 mm to 28 mm, the internal pressure drop of the evaporator decreases by 45.83% and the heat exchange increases by 18.34%. When the number of evaporator slices increases from 16 to 24, the heat transfer increases first and then decreases, with an overall decrease of 2.86% and an increase of 87.67% in the internal pressure drop of the evaporator. The inclination angle of the corrugation changes from 30° to 60°, and the heat transfer capacity and pressure drop increase. After the inclination angle is greater than 60°, the heat transfer capacity and resistance decrease. The results are of great significance to system optimization design and engineering practical application.

Heat Transfer Performance of LiF–NaF–KF Salt in a Corrugated Receiver Tube With Non-Uniform Solar Flux

2017 ◽  
Author(s):  
Chaxiu Guo ◽  
Dongwei Zhang ◽  
Junjie Zhou ◽  
Wujun Zhang ◽  
Xinli Wei
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Tube Wall ◽  
Uniform Heat Flux ◽  
Transfer Performance ◽  
Corrugated Tube ◽  
The Heat Transfer Coefficient

The heat flux on the receiver tube is non-uniform because of uneven solar flux and receiver structure, which causes overheating and thermal stress failure of receiver and affected safe operations of the Concentrated Solar Power (CSP) system. In order to reduce the temperature difference in receiver tube wall and improve the efficiency of CSP system, the ternary eutectic salt LiF-NaF-KF (46.5-11.5-42 wt.%, hereafter FLiNaK), which has a better high thermal stability than that of nitrate salts at operating temperature of 900 °C, is selected as HTF, and heat transfer performance of FLiNaK in a corrugated receive tube with non-uniform heat flux is simulated by CFD software in the present work. The numerical results reveal that the non-uniform heat flux has a great influence on the temperature distributions of the receive tube and FLiNaK salt. Compared with the result of bare tube, the corrugated tube can not only significantly reduce the temperature difference in tube wall and salt by improving the uniformity of temperature distribution but also enhance the heat transfer of the salt, where the heat transfer coefficient increases with the Reynolds number and heat flux. Moreover, the enhanced effect of the corrugated tube depends on both the pitch and the height of ridges. It is found that the heat transfer coefficient of the salt gets a maximum when the ratio of the height of ridge to the pitch is 0.2. The research presented here may provide guidelines for design optimization of receiver tube in CSP system.

Effect of Endwall Contouring on a Transonic Turbine Blade Passage: Part 2—Heat Transfer Performance

2012 ◽  
Author(s):  
Kapil V. Panchal ◽  
Santosh Abraham ◽  
Srinath V. Ekkad ◽  
Wing Ng ◽  
Andrew S. Lohaus ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Aerodynamic Performance ◽  
Transfer Performance ◽  
Blade Passage ◽  
Transonic Turbine ◽  
Endwall Contouring ◽  
The Heat Transfer Coefficient

Contouring of turbine endwalls has been widely studied for aerodynamic performance improvement of turbine passages. However, it is equally important to investigate the effect of contouring on endwall heat transfer, because a substantial increase in endwall heat transfer due to contouring will render the design impractical. In this paper, the effect of contouring on endwall heat transfer performance of a high-turning HP-turbine blade passage, operating under transonic exit Mach number conditions, is reported. Three endwall geometries were experimentally investigated at three different passage exit Mach numbers, 0.71, 0.88(design) and 0.95, for their heat transfer performance. One endwall is a non-contoured baseline endwall and the other two are contoured endwall geometries. One of the contoured endwall geometry was generated with the goal of reduction in stagnation pressure losses and the other was generated with the goal of reduced overall heat transfer through the endwall. The experiments were carried out in Virginia Tech’s transient, blow down, transonic linear cascade facility. Endwall surface temperatures were measured using infrared thermography technique. Local heat transfer coefficient values were calculated using the measured temperatures. The heat transfer coefficient values were then related to the endwall geometries using a camera matrix model. The measurement technique and the methodology for the post-processing of the heat transfer coefficient data have been presented in detail. Details of the flow behavior for these endwalls were obtained using CFD simulations and have been used to assist the interpretation of the experimental results. In this study, the heat transfer performance of the contoured endwalls in comparison to the non-contoured baseline case is presented. Both the contoured endwalls demonstrated a significant reduction in the overall average heat transfer coefficient values. The surface heat transfer coefficient distributions also indicated a reduction in the level of hot spots for most of the endwall surface. However, increase in the heat transfer coefficient values was observed especially in the area near the leading edge. The results indicate that, in addition to a probable improvement in aerodynamic performance, endwall contouring may also be used to improve the heat transfer performance of turbine passages. Additionally, aerodynamic behavior of these endwalls is discussed in detail in the companion paper GT2012-68425, “Effect of endwall contouring on a transonic turbine endwall: Part 1 – Aerodynamic performance.”

Investigations on the Condensation Heat Transfer Performance of Stainless Steel Edge-Shaped Finned Tubes

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Zhen-ping Wan ◽  
Xiao-wu Wang ◽  
Xiao-xia Zhang ◽  
Yong Tang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Temperature Difference ◽  
Heat Transfer Performance ◽  
Three Dimensional ◽  
Condensation Heat Transfer ◽  
Transfer Performance ◽  
Shell Side ◽  
Finned Tubes

The third-generation enhanced heat transfer technologies, such as three-dimensional fin and dimple, are still important means of improving energy efficiency. This paper analyzes the condensation heat transfer performances of three edge-shaped finned tubes that were fabricated using the plowing–extruding process. Experimental results show that the shell-side heat transfer coefficient decreases with increases of heat flux and temperature difference between wall and vapor. The edge-shaped finned tubes exhibit better heat transfer performance than smooth tubes. At the identical temperature difference between the wall and the vapor, the shell-side heat transfer coefficient of the edge-shaped finned tubes is approximately 1.7–2.6 times larger than that of the smooth tubes. At the identical temperature difference between the wall and the vapor, the shell-side heat transfer coefficient of edge-shaped finned tubes is also higher than the reported value in the literature. The excellent performance of the edge-shaped finned tubes comes from the coordination of enhancement from the three-dimensional fins, dimples, and grooves. Finned tubes with grooves fabricated along the left direction have higher and thinner fins and therefore show better heat transfer performance. The shell-side heat transfer coefficients of edge-shaped finned tubes increase with plowing–extruding depth and feed increasing.

Analysis on the Heat Transfer Performance of Jacketed Tube Heat Exchanger with Different Finned Array

2013 ◽  
Vol 860-863 ◽  
pp. 1478-1483
Author(s):  
Zhong Chao Zhao ◽  
Hao Jun Mi ◽  
Long Yun
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Tube Heat Exchanger ◽  
The Heat Transfer Coefficient

The heat transfer performance of heat exchanger dependents on the pattern of finned array. The heat transfer coefficient of jacketed tube heat exchanger with and without finned array was investigated by computational fluid dynamics. The results reveal that: the heat transfer coefficient of jacketed tube heat exchanger with in-line-fin and staggered-fin increase to the 87.8% and 98.2% of that without finned array, respectively, and with 35.1% and 37.6% increments of pressure drop correspondingly. The heat transfer coefficient of heat exchanger with staggered-fin increased to 5.4% compared with that with in-line-fin.

Experimental investigation into spray cooling heat transfer performance of Al2O3-water nanofluid with different subcooling degrees

2021 ◽  
pp. 095440892110378
Author(s):  
Tong-Bou Chang ◽  
Tsung-Han Lin ◽  
Jhong-Wei Huang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Gradual Increase ◽  
Heated Surface ◽  
Operating Time ◽  
Spray Cooling ◽  
Transfer Performance ◽  
The Heat Transfer Coefficient

This study investigated the spray cooling heat transfer performance of Al2O3-water nanofluid given four different subcooling degrees (0 °C, 10 °C, 20 °C, and 30 °C). The results showed that the subcooled nanofluids were ranked in order of a reducing spray cooling heat transfer performance as follows: 20 °C, 10 °C, 0 °C, and 30 °C. On average, the heat transfer coefficient obtained using the nanofluid with 20 °C subcooling was around 8.3%, 8.6%, and 15.6% higher than that obtained with 10 °C, 0 °C, and 30 °C subcooling, respectively. However, the heat transfer performance decreased with an increasing spray operating time. The scanning electron microscopy observations showed that the reduction in the heat transfer coefficient was the result of a gradual increase in the thickness of the nano-adsorption layer on the heated surface as the spray operating time increased.

Production Process and Heat Transfer Performance of 10/316 Clad Tube

2014 ◽  
Vol 1081 ◽  
pp. 270-274
Author(s):  
Zui Xian Yu ◽  
Xue Sheng Wang ◽  
Qin Zhu Chen
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Heat Transfer Coefficient ◽  
Carbon Steel ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Steel Tube ◽  
Stainless Steel Tube ◽  
Transfer Performance ◽  
Clad Tube

A new preparation technique of carbon steel/stainless steel clad tube was introduced, and the contact surface was well combined. Meanwhile, with the using of tube heat exchanger, the experiment on the heat transfer performance of the clad tube was done. Comparing the 10/316 clad tube and the 316 stainless steel tube, the effects on the heat transfer performance of 316 stainless steel tube attached to carbon steel was evaluated. It is showed that overall heat transfer coefficient of 10/316 clad tubes is higher than that of stainless steel tube. The average heat transfer coefficient of 10/316 clad tubes is about 18.7%~34.4% higher than that of stainless steel tube. Experimental investigation indicates that, by brazing and cold drawing, the 10/316 clad tube was well combined and the thermal conductivity was better than that of stainless steel tube.

Heat Transfer Performance of Different Nanofluids Flows in a Helically Coiled Heat Exchanger

2013 ◽  
Vol 832 ◽  
pp. 160-165 ◽  
Author(s):  
Mohammad Alam Khairul ◽  
Rahman Saidur ◽  
Altab Hossain ◽  
Mohammad Abdul Alim ◽  
Islam Mohammed Mahbubul
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Transfer Performance

Helically coiled heat exchangers are globally used in various industrial applications for their high heat transfer performance and compact size. Nanofluids can provide excellent thermal performance of this type of heat exchangers. In the present study, the effect of different nanofluids on the heat transfer performance in a helically coiled heat exchanger is examined. Four different types of nanofluids CuO/water, Al2O3/water, SiO2/water, and ZnO/water with volume fractions 1 vol.% to 4 vol.% was used throughout this analysis and volume flow rate was remained constant at 3 LPM. Results show that the heat transfer coefficient is high for higher particle volume concentration of CuO/water, Al2O3/water and ZnO/water nanofluids, while the values of the friction factor and pressure drop significantly increase with the increase of nanoparticle volume concentration. On the contrary, low heat transfer coefficient was found in higher concentration of SiO2/water nanofluids. The highest enhancement of heat transfer coefficient and lowest friction factor occurred for CuO/water nanofluids among the four nanofluids. However, highest friction factor and lowest heat transfer coefficient were found for SiO2/water nanofluids. The results reveal that, CuO/water nanofluids indicate significant heat transfer performance for helically coiled heat exchanger systems though this nanofluids exhibits higher pressure drop.

Research on Heat Transfer Performance of Water Film for Outside the Tubes of the Microscale Evaporative Condenser

2009 ◽  
Author(s):  
Minghui Hu ◽  
Dongsheng Zhu ◽  
Jialong Shen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Water Film ◽  
Transfer Performance ◽  
Air Velocity ◽  
Microscale Heat Transfer ◽  
High Heat Transfer ◽  
Spray Density

It is requested to develop a microscale and high performance heat exchanger for small size energy equipments. The heat transfer performance of the water film on the condensing coils of the microscale evaporative condenser was studied for a single-stage compressed refrigeration cycle system. Under various operation conditions, the effects of the spray density and the head-on air velocity on the heat transfer performance of the water film were investigated. The results show that the microscale heat transfer coefficient of the water film αw increases with the increase of spray density and decreases with the increase of head-on air velocity. The results indicate that the key factor affecting the microscale heat transfer of the water film is the spray density. As the results, it is measured that the present device attained high heat transfer quantity despite the weight is light. In addition, via regression analysis of the experimental data, the correlation equation for calculating the microscale heat transfer coefficient of the water film was obtained, its regression correlation coefficient R is 0.98 and the standard deviation is 7.5%. Finally, the correlations from other works were compared. The results presented that the experimental correlation had better consistency with the correlations from other works. In general, the obtained experimental results of the water film heat transfer are helpful to the design and practical operation of the microscale evaporative condensers.

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