Study on the heat-flow controllable heat exchanger (1st report): Thermal characteristics of heat-flow controllable heat exchanger

Solar Energy ◽  
1994 ◽  
Vol 52 (5) ◽  
pp. 451-456 ◽  
Author(s):  
Michio Yanadori ◽  
Masayoshi Hamano ◽  
Tomohiro Kawano
Keyword(s):  
Heat Exchanger ◽  
Heat Flow ◽  
Thermal Characteristics

Heat and Mass Transfer to Air in a Cross Flow Heat Exchanger with Surface Deluge Cooling

2016 ◽  
Vol 24 (01) ◽  
pp. 1650002 ◽  
Author(s):  
Andrea Diani ◽  
Luisa Rossetto ◽  
Roberto Dall’Olio ◽  
Daniele De Zen ◽  
Filippo Masetto
Keyword(s):  
Heat Exchanger ◽  
Heat Flow ◽  
Flow Rate ◽  
Data Center ◽  
Heat Dissipation ◽  
Cross Flow ◽  
Critical Conditions ◽  
Heat Flow Rate ◽  
External Temperature ◽  
Flow Heat

Cross flow heat exchangers, when applied to cool data center rooms, use external air (process air) to cool the air stream coming from the data center room (primary air). However, an air–air heat exchanger is not enough to cope with extreme high heat loads in critical conditions (high external temperature). Therefore, water can be sprayed in the process air to increase the heat dissipation capability (wet mode). Water evaporates, and the heat flow rate is transferred to the process air as sensible and latent heat. This paper proposes an analytical approach to predict the behavior of a cross flow heat exchanger in wet mode. The theoretical results are then compared to experimental tests carried out on a real machine in wet mode conditions. Comparisons are given in terms of calculated versus experimental heat flow rate and evaporated water mass flow rate, showing a good match between theoretical and experimental values.

scholarly journals Thermal performance in a tubular heat exchanger with deltawinglets

2018 ◽  
Vol 192 ◽  
pp. 02062
Author(s):  
Pattarapan Tongyote ◽  
Pongjet Promvonge ◽  
Nattawoot Depaiwa ◽  
Withada Jedsadaratanachai
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Performance ◽  
Thermal Characteristics ◽  
Test Tube ◽  
Turbulent Regime ◽  
Airflow Rate ◽  
Tubular Heat Exchanger ◽  
Experimental Heat ◽  
Constant Wall Heat Flux

The paper presents an experimental heat transfer enhancement study in a tubular heat exchanger fitted with delta-winglets. The experimental work was conducted by varying the airflow rate in the test tube having a constant wall heat-flux for turbulent regime, Reynolds number (Re) from 5200 to 23,000. Effects of three pitch ratios (PR=P/D=1.5, 2.0 and 3.0) and two attack angles, α = 45° and 60°, of the winglets at a single blockage ratio (BR=b/D = 0.15) on thermal characteristics are examined. The experimental results show that the winglet-inserted tube yields, respectively, the heat transfer, friction factor and thermal performance in the form of TEF around 1.99–4.08, 4.9–14.3 times higher than the plain tube and 0.85–1.85, depending on the operating condition.

scholarly journals Design of Flue Gas-Air Heat Exchanger for Regeneration of Desiccant System

2018 ◽  
Vol 225 ◽  
pp. 05006 ◽  
Author(s):  
Shaymaa H. Abdulmalek ◽  
Hussain H. Al-Kayiem ◽  
Aklilu T. Baheta ◽  
Ali A. Gitan
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Waste Heat ◽  
Thermal Characteristics ◽  
Tube Diameter ◽  
Fuel Gas ◽  
Overall Heat Transfer Coefficient ◽  
Heat Exchanger Design

Heat recovering from biogas waste energy requires robust heat exchanger design. This paper presents the design of fuel gas-air heat exchanger (FGAHE) for recovering waste heat from biogas burning to regenerate desiccant material. Mathematical model was built to design the FGAHE based on logarithmic mean temperature difference (LMTD) and staggered tube bank heat transfer correlations. MATLAB code was developed to solve the algorithm based on overall heat transfer coefficient iteration technique. The effect on tube diameter on design and thermal characteristics of FGAHE is investigated. The results revealed that the smaller tube diameter leads to smaller heat transfer area and tube. On the other hand, the overall heat transfer coefficient and Nusselt numbers have larger rates at smaller tube diameter. In conclusion, the nominated tube diameter for FGAHE is the smaller diameter of 0.0127 m due to the high thermal performance.

scholarly journals Performance of Air-Cooled Heat Exchanger with Laminar, Transitional, and Turbulent Tube Flow

2018 ◽  
Vol 240 ◽  
pp. 02012
Author(s):  
Dawid Taler
Keyword(s):  
Nusselt Number ◽  
Heat Exchanger ◽  
Heat Flow ◽  
Friction Factor ◽  
Flow Rate ◽  
Empirical Relationship ◽  
Heat Flow Rate ◽  
Transition Flow ◽  
Water Side ◽  
Wide Range

Some air-cooled heat exchangers, especially in air conditioning and heating installations, heat pumps, as well as car radiators, work in a wide range of loads when the liquid flow in the tubes can be laminar, transitional or turbulent. In this paper, a semi-empirical and empirical relationship for the Nusselt number on the liquid-side in the transitional and turbulent range was derived. The friction factor in the transition flow range Rew,trb ≤ Rew ≤ Rew,tre was calculated by linear interpolation between the values of the friction factor for Rew,trb =2,100 and Rew,tre =3,000. Based on experimental data for a car radiator, empirical heat transfer relationships for the air and water-side were found by using the least squares method. The water temperature at the outlet of the heat exchanger was calculated using P-NTU (effectiveness-number of transfer units) method. The heat flow rate from water to air was calculated as a function of the water flow rate to compare it with the experimental results. The theoretical and empirical correlation for the water-side Nusselt number developed in the paper were used when determining the heat flow rate. The calculation results agree very well with the results of the measurements.

An analysis of heat flow through a borehole heat exchanger validated model

2012 ◽  
Vol 92 ◽  
pp. 523-533 ◽  
Author(s):  
Georgios A. Florides ◽  
Paul Christodoulides ◽  
Panayiotis Pouloupatis
Keyword(s):  
Heat Exchanger ◽  
Heat Flow ◽  
Borehole Heat Exchanger ◽  
Flow Through

scholarly journals Thermal Characteristics of a Primary Surface Heat Exchanger with Corrugated Channels

Entropy ◽  
2015 ◽  
Vol 18 (1) ◽  
pp. 15 ◽  
Author(s):  
Jang-Won Seo ◽  
Chanyong Cho ◽  
Sangrae Lee ◽  
Young-Don Choi
Keyword(s):  
Heat Exchanger ◽  
Thermal Characteristics ◽  
Surface Heat ◽  
Surface Heat Exchanger

Thermal Optimization of Exhaust-Based Thermoelectric Generator

2013 ◽  
Vol 743-744 ◽  
pp. 88-93 ◽  
Author(s):  
Ya Dong Deng ◽  
Shan Chen ◽  
Xun Liu
Keyword(s):  
Heat Exchanger ◽  
Thermal Performance ◽  
High Performance ◽  
Thermoelectric Generator ◽  
Thermal Characteristics ◽  
Interface Temperature ◽  
Cfd Simulations ◽  
Exhaust Heat ◽  
Internal Structures ◽  
Plate Shape

The potential for automotive exhaust heat based thermoelectric generator (TEG) has been increased with continuously advances in thermoelectric technology. The thermal performance of the heat exchanger in exhaust-based TEG was analyzed. In terms of interface temperature and thermal uniformity, the thermal characteristics of the heat exchangers with different internal structures, materials and thicknesses were discussed. CFD simulations and infrared experiments on a high-performance production engine with a dynamometer were carried out. It was proved that the plate-shape heat exchanger made of brass with internal baffles and the thickness of 3mm, obtained a relatively optimal thermal performance, and it will help to improve the thermal performance of the TEG.

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