scholarly journals Experimental heat and mass transfer studies on horizontal falling film absorber using water-lithium bromide

2020 ◽  
Vol 24 (3 Part B) ◽  
pp. 1923-1934 ◽  
Author(s):  
Banu Arshi ◽  
N.M. Sudharsan
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Heat And Mass Transfer ◽  
Water Flow Rate ◽  
Lithium Bromide ◽  
Cooling Water ◽  
Horizontal Tube ◽  
Working Fluid ◽  
Falling Film ◽  
Cooling Water Flow Rate

Vapour absorption systems are more viable technology option in energy and environmental perspective in cooling and heating applications. Among the four major components of vapour absorption system, the absorber plays a vital role in deciding the performance, size and cost. Horizontal falling film absorbers comparatively contain good heat and mass transfer characteristics than other type of absorbers for working fluids such as water-lithium bromide. Literature shows that experimental approach of performance evaluation of absorber is more realistic and accurate than the theoretical approach. Hence in the present work, a detail experimental study has been done on horizontal tube falling film absorber using water-lithium bromide as a working fluid. The set-up consists of two major components viz. absorber and generator. Absorber contains three columns of tubes, with eight rows in each column. Detailed parametric study has been done by considering influence of spray density, cooling water-flow rate, cooling water temperature and concentration on solution temperatures, cooling water temperatures, inlet and outlet concentrations, heat flux, mass flux, heat transfer coefficient, and mass transfer coefficient with the help of plots. Results have been validated and literature gaps have been discussed.

Comparison of Heat and Mass Transfer Characteristics of Absorption of R134a in DMAC and DMF for a Falling Film Horizontal Tube Absorber

2014 ◽  
Author(s):  
Kamal Kant Yadu ◽  
Shaligram Tiwari ◽  
Prakash Maiya Manoor
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Heat And Mass Transfer ◽  
Numerical Technique ◽  
Horizontal Tube ◽  
Computer Code ◽  
Mean Value ◽  
Falling Film ◽  
Transfer Characteristics

The present work is a comparative study of heat and mass transfer behaviour during the absorption of R134a (1, 1, 1, 2 Tetrafluroethane) vapour into absorbents, DMAC (N, N-Dimethylacetamide) and DMF (N, N-Dimethylformamide). Initially, the heat and mass transfer characteristics for absorption of R134a into DMF for a falling film horizontal tubular absorber have been investigated by employing a two-dimensional numerical technique. The related governing equations are solved using a developed computer code in MATLAB. Then, a comparison of absorption characteristics of R134a-DMAC and R134a-DMF is made. For the mean value of operating parameters considered, the R134a-DMF solution absorbs more due to higher diffusion coefficient value of DMF than DMAC. The mass transfer coefficient is observed to decrease at a steeper rate at the entrance of the first tube for both working fluids, after which gradual decrease in the mass transfer coefficient is observed further downstream.

scholarly journals Modeling of conjugated heat and mass transfer in the entrance region of falling liquid film at various values of the Froude number

2018 ◽  
Vol 194 ◽  
pp. 01007
Author(s):  
Maria V. Bartashevich
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Liquid Film ◽  
Froude Number ◽  
Heat And Mass Transfer ◽  
Water Solution ◽  
Lithium Bromide ◽  
Entrance Region ◽  
Falling Film ◽  
Falling Liquid Film

Mathematical model of conjugated heat and mass transfer in absorption on the entrance region of the semi-infinite liquid film of lithium bromide water solution is investigated for different values of Froude number. The calculations shown that larger values of Froude number corresponds to a smaller thickness of the falling film. It was demonstrated that for large values of the Froude number the heat transfer from the surface is greater than for smaller values.

Effects of a Nonabsorbable Gas on Interfacial Heat and Mass Transfer for the Entrance Region of a Falling Film Absorber

1996 ◽  
Vol 118 (1) ◽  
pp. 45-49 ◽  
Author(s):  
T. A. Ameel ◽  
H. M. Habib ◽  
B. D. Wood
Keyword(s):  
Mass Transfer ◽  
Water Vapor ◽  
Analytical Solution ◽  
Liquid Film ◽  
Heat And Mass Transfer ◽  
Vertical Wall ◽  
Lithium Bromide ◽  
Entrance Region ◽  
Falling Film ◽  
Aqueous Lithium Bromide

An analytical solution is presented for the effect of air (nonabsorbable gas) on the heat and mass transfer rates during the absorption of water vapor (absorbate) by a falling laminar film of aqueous lithium bromide (absorbent), an important process in a proposed open-cycle solar absorption cooling system. The analysis was restricted to the entrance region where an analytical solution is possible. The model consists of a falling film of aqueous lithium bromide flowing down a vertical wall which is kept at uniform temperature. The liquid film is in contact with a gas consisting of a mixture of water vapor and air. The gas phase is moving under the influence of the drag from the falling liquid film. The governing equations are written with a set of interfacial and boundary conditions and solved analytically for the two phases. Heat and mass transfer results are presented for a range of uniform inlet air concentrations. It was found that the concentration of the nonabsorbable gas increases sharply at the liquid gas interface. The absorption of the absorbate in the entrance region showed a continuous reduction with an increase in the amount of air.

Numerical Study on Heat and Mass Transfer of Plate Falling Film Absorber with Wire-Meshed Fins

2012 ◽  
Vol 204-208 ◽  
pp. 4305-4314
Author(s):  
Jing Jing Zhang ◽  
Dan Dan Zhao ◽  
Lu Chun Wan ◽  
Bao Huai Zhang ◽  
Ya Ping Chen
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat And Mass Transfer ◽  
Absorption Rate ◽  
Numerical Study ◽  
Mass Transfer Process ◽  
Falling Film ◽  
Better Than

A mathematical model of heat and mass transfer process in plate falling film absorber with wire-meshed fins was developed. The model could predict temperature and concentration distribution as well as the solution side heat transfer coefficient and the absorption rate. The results verify that heat and mass transfer performance of the plate falling film absorber with wire-meshed fins is better than the past absorber. Compared with the plate falling film absorber without fins, heat transfer coefficient of the absorber in this article increases 1.06 times and the absorption rate increases 2.32 times.

scholarly journals Heat Transfer Characteristics of High-Temperature Dusty Flue Gas from Industrial Furnaces in a Granular Bed with Buried Tubes

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3589
Author(s):  
Shaowu Yin ◽  
Feiyang Xue ◽  
Xu Wang ◽  
Lige Tong ◽  
Li Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Water Flow ◽  
Flow Rate ◽  
Waste Heat ◽  
Water Flow Rate ◽  
Cooling Water ◽  
Granular Bed ◽  
Cooling Water Flow Rate

Experimental heat transfer equipment with a buried tube granular bed was set up for waste heat recovery of flue gas. The effects of flue gas inlet temperature (1096.65–1286.45 K) and cooling water flow rate (2.6–5.1 m3/h) were studied through experiment and computational fluid dynamics’ (CFD) method. On the basis of logarithmic mean temperature difference method, the total heat transfer coefficient of the granular bed was used to characterize its heat transfer performance. Experimental results showed that the waste heat recovery rate of the equipment exceeded 72%. An increase in the cooling water flow rate and inlet gas temperature was beneficial to recovering waste heat. The cooling water flow rate increases from 2.6 m3/h to 5.1 m3/h and the recovery rate of waste heat increases by 1.9%. Moreover, the heat transfer coefficient of the granular bed increased by 4.4% and the inlet gas temperature increased from 1096.65 K to 1286.45 K. The recovery rate of waste heat increased by 1.7% and the heat transfer coefficient of the granular bed rose by 26.6%. Therefore, experimental correlations between the total heat transfer coefficient of a granular bed and the cooling water flow rate and inlet temperature of dusty gas were proposed. The CFD method was used to simulate the heat transfer in the granular bed, and the effect of gas temperature on the heat transfer coefficient of granular bed was studied. Results showed that the relative error was less than 2%.

scholarly journals Experimental Study of the Heat-Transfer Performance of an Extra-Long Gravity-Assisted Heat Pipe Aiming at Geothermal Heat Exploitation

2021 ◽  
Vol 13 (22) ◽  
pp. 12481
Author(s):  
Jiwen Cen ◽  
Feng Li ◽  
Tingliang Li ◽  
Wenbo Huang ◽  
Juanwen Chen ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Water Flow Rate ◽  
Cooling Water ◽  
Filling Ratio ◽  
Working Fluid ◽  
Enhanced Geothermal Systems ◽  
Transfer Performance ◽  
Cooling Water Flow Rate

The installation and operation of enhanced geothermal systems (EGS) involves many challenges. These challenges include the high cost and high risk associated with the investment capital, potential large working-fluid leakage, corrosion of equipment, and subsiding land. A super-long heat pipe can be used for geothermal exploitation to avoid these problems. In this paper, a high aspect-ratio heat pipe (30 m long, 17 mm in inner diameter) is installed vertically. Experiments are then carried out to study its heat-transfer performance and characteristics using several filling ratios of deionized water, different heating powers, and various cooling-water flowrates. The results show that the optimal filling-ratio is about 40% of the volume of the vaporizing section of the heat pipe. Compared with a conventional short heat pipe, the extra-long heat pipe experiences significant thermal vibration. The oscillation frequency depends on the heating power and working-fluid filling ratio. With increasing cooling-water flow rate, the heat-transfer rate of the heat pipe increases before it reaches a plateau. In addition, we investigate the heat-transfer performance of the heat pipe for an extreme working-fluid filling ratio; the results indicate that the lower part of the heat pipe is filled with vapor, which reduces the heat-transfer to the top part. Based on the experimental data, guidelines for designing a heat pipe that can be really used for the exploitation of earth-deep geothermal energy are analyzed.

An Experimental Study on Heat and Mass Transfer in a Helical Absorber Using LiBr+LiI+LiNO3+LiCl Solution

2000 ◽  
Author(s):  
Jung-In Yoon ◽  
Choon-Geun Moon ◽  
Oh-Kyung Kwon ◽  
Eunpil Kim
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Experimental Study ◽  
Heat And Mass Transfer ◽  
Working Fluid ◽  
Transfer Performance ◽  
Falling Film ◽  
Absorption Chiller ◽  
Libr Solution ◽  
Cylindrical Form

Abstract An experimental study has been performed to investigate the heat and mass transfer performance in a falling film absorber of a domestic small-sized absorption chiller/heater. The components of the chiller/heater were concentrically arranged in a cylindrical form with low temperature generator, an absorber and an evaporator from the center. The arrangement of such a helical-type heat exchanger allows to make the system more compact as compared to a conventional one. As a working fluid, the LiBr+LiI+LiNO3+LiCl solution is used to get improved heat transfer. The heat and mass flux performance of the LiBr+LiI+LiNO3+LiCl solution shows 2 ∼ 5% increase than that of the LiBr solution. When a surfactant in the LiBr+LiI+LiNO3+LiCl solution is used, the performance of heat and mass transfer improves 15 ∼ 20%. This result shows the LiBr+LiI+LiNO3+LiCl solution with a surfactant can be applied to a small-sized absorption chiller/heater.

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