Evaporative Heat Transfer Analysis of a Heat Pipe With Hybrid Axial Groove

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Lizhan Bai ◽  
Guiping Lin ◽  
G. P. Peterson
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Liquid Film ◽  
Transfer Coefficient ◽  
Flow Resistance ◽  
Heat Pipes ◽  
Low Flow ◽  
Circular Channel ◽  
Evaporative Heat Transfer ◽  
Evaporative Heat Transfer Coefficient

Through the application of thin film evaporation theory and the fundamental operating principles of heat pipes, a hybrid axial groove has been developed that can greatly enhance the performance characteristics of conventional heat pipes. This hybrid axial groove is composed of a V-shaped channel connected with a circular channel through a very narrow longitudinal slot. During the operation, the V-shaped channel can provide high capillary pressure to drive the fluid flow and still maintain a large evaporative heat transfer coefficient. The large circular channel serves as the main path for the condensate return from the condenser to the evaporator and results in a very low flow resistance. The combination of a high evaporative heat transfer coefficient and a low flow resistance results in considerable enhancement in the heat transport capability of conventional heat pipes. In the present work, a detailed mathematical model for the evaporative heat transfer of a single groove has been established based on the conservation principles for mass, momentum and energy, and the modeling results quantitatively verify that this particular configuration has an enhanced evaporative heat transfer performance compared with that of conventional rectangular groove, due to the considerable reduction in the liquid film thickness and a corresponding increase in the evaporative heat transfer area in both the evaporating liquid film region and the meniscus region.

scholarly journals FORCED CONVECTION DRYING OF INDIAN GROUNDNUT: AN EXPERIMENTAL STUDY

2017 ◽  
Vol 15 (3) ◽  
pp. 467
Author(s):  
Ravinder Kumar Sahdev ◽  
Mahesh Kumar ◽  
Ashwani Kumar Dhingra
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Forced Convection ◽  
Experimental Error ◽  
Linear Regression Analysis ◽  
Convective Heat Transfer Coefficient ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Evaporative Heat Transfer

In this paper, convective and evaporative heat transfer coefficients of the Indian groundnut were computed under indoor forced convection drying (IFCD) mode. The groundnuts were dried as a single thin layer with the help of a laboratory dryer till the optimum safe moisture storage level of 8 – 10%. The experimental data were used to determine the values of experimental constants C and n in the Nusselt number expression by a simple linear regression analysis and consequently, the convective heat transfer coefficient (CHTC) was determined. The values of CHTC were used to calculate the evaporative heat transfer coefficient (EHTC). The average values of CHTC and EHTC were found to be 2.48 W/m2 oC and 35.08 W/m2 oC, respectively. The experimental error in terms of percent uncertainty was also estimated. The experimental error in terms of percent uncertainty was found to be 42.55%. The error bars for convective and evaporative heat transfer coefficients are also shown for the groundnut drying under IFCD condition.

scholarly journals Using artificial neural network for predicting heat transfer coefficient during flow boiling in an inclined channel

2020 ◽  
pp. 238-238
Author(s):  
Adel Bouali ◽  
Salah Hanini ◽  
Brahim Mohammedi ◽  
Mouloud Boumahdi
Keyword(s):  
Neural Network ◽  
Heat Transfer ◽  
Experimental Data ◽  
Artificial Neural Network ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Boiling ◽  
Low Flow ◽  
Inclined Channel ◽  
Artificial Neural

The flow and heat transfer characteristics in a nuclear power plant in the event of a serious accident are simulated by boiling water in an inclined rectangular channel. In this study an artificial neural network model was developed with the aim of predicting heat transfer coefficient (HTC) for flow boiling of water in inclined channel, the network was designed and trained by means of 520 experimental data points that were selected from within the literature. orientation ,mass flux, quality and heat flow which were employed to serve as variables of input of multiple layer perceptron (MLP) neural network, whereas the analogous HTC was selected to be its output. Via the method of trial-and-error, MLP network with 30 neurons in the hidden layer was attained as optimal ANN structure. The fact that is was enabled to predict accurately the HTC. For the training set, the mean relative absolute error (MRAE) is about 0.68 % and the correlation coefficient (R) is about 0.9997. As for the testing and validation set they are respectively about 0.60 % and 0.9998 and about 0.79 % and 0.9996. The comparison of the developed ANN model with experimental data and empirical correlations in vertical channel under the low flow rate and low quality shows a good agreement.

scholarly journals An Experimental Investigation on the Heat Transfer Coefficient of Oscillating Heat Pipes

2013 ◽  
Vol 732-733 ◽  
pp. 78-82
Author(s):  
Ling Gao ◽  
Wen Guang Geng ◽  
Xiao Xu Ma ◽  
Xiu Li Ma ◽  
Guang Liang Luo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Transfer Coefficient ◽  
Relative Humidity ◽  
Transfer Coefficient ◽  
Convective Heat Transfer Coefficient ◽  
Heat Pipes ◽  
Oscillating Heat Pipe ◽  
Hot Air ◽  
The Relationship

This paper presents an experimental study on total heat transfer coefficient (ht) in oscillating heat pipe heat exchanger hot air flow tunnels, ht plays an important role in the oscillating heat pipes design process. In this paper, ht and the convective heat transfer coefficient (h) was investigated by experimentally and theoretical calculation respectively. From experimental study, the relationship between the ratio of heat transfer coefficient and the relative humidity is obtained. The results show that the ratio of ht to h increases from 5 to 20 as the relative humidity of the hot gas increasing from 19.22% to 60%. According to the experimental data, a matched curve and an empirical equation were presented, which can be described as ht=h(1.87783+0.09631x+0.0032x2).

scholarly journals Experimental investigation of heat transfer of flowing liquid film with inserted metal foam layer subjected to air jet impingement

2019 ◽  
Vol 23 (5 Part B) ◽  
pp. 3093-3104
Author(s):  
Yunsong Zhang ◽  
Wei Chen ◽  
Wei Li ◽  
Xiao Zhu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Liquid Film ◽  
Transfer Coefficient ◽  
Porous Layer ◽  
Metal Foam ◽  
Jet Impingement ◽  
Heated Wall ◽  
Flowing Liquid ◽  
Air Jet

In this paper, coupling the air jet impingement and the copper metal foam above flowing liquid film were employed to enhance the heat transfer. The thickness of flowing liquid film can be controlled owing to the application of the metal foam above the film, and its solid matrix extends the air-liquid-solid interface of heating surface. The evaporated water can be supplied by the capillary force in the porous layer. The experiments were conducted to investigate the performances of the flowing liquid film with inserted porous layer subjected to impinging jet air. The air jet velocity, the flow rate and thicknesses of the liquid film as well as the porosity of metal foam influence the surface temperature of heated wall and the corresponding local heat transfer coefficient greatly. The change ratios of heat transfer coefficient due to the above factors were presented. More cooling can be obtained on the heated wall in the flowing liquid film with inserted porous layer subjected to impinging jet air while the higher liquid film velocity and air jet velocity, the thinner liquid film and the lower porosity of metal foam occur.

Sign in / Sign up

Export Citation Format

Share Document