scholarly journals Calculation and Experimental Study of Heat Exchange in a System of Plane-Parallel Channels with Surface Intensifiers

2021 ◽  
Vol 17 (2) ◽  
pp. 211-220
Author(s):  
S. I. Kaskov ◽  
Keyword(s):  
Experimental Study ◽  
Heat Exchange ◽  
Heat Removal ◽  
Air Cooling ◽  
Airflow Rate ◽  
Power Semiconductor ◽  
Average Temperature ◽  
Plane Parallel ◽  
Parallel Channels ◽  
The Difference

This paper presents the results of numerical investigation, calculation analysis and experimental study of heat exchange in a system of plane-parallel channels formed by rectangular fins, which are applied in a heat removal device using heat tubes for power semiconductor energy converters. Passive cooling (heat removal by radiation and natural convection) and active cooling (heat removal by radiation and forced convection) are investigated for various velocities of air cooling of fins by spherical vortex generators applied to its surface. A comparative analysis of the results is carried out for the average effective heat removal resistance and for the average temperature at the ends of the fins. The application of numerical modeling to solve such problems confirms the effectiveness of computational technologies. The difference between the results of the study ranges from 10 to 16% depending on the airflow rate.

HEAT EXCHANGE PROCESSES IN POWER SEMICONDUCTOR CONVERTER INSTALLATIONS WITH EVAPORATIVE AIR COOLING

2017 ◽  
pp. 140-147
Author(s):  
Igor Kiselev ◽  
Sergey Urushev ◽  
Igor Ivanov ◽  
Yulia Vodopyanova
Keyword(s):  
Heat Exchange ◽  
Semiconductor Devices ◽  
Practical Importance ◽  
Structural Features ◽  
Air Cooling ◽  
Two Phase ◽  
Power Semiconductor ◽  
Semiconductor Converter ◽  
Exchange Processes ◽  
Improve Reliability

Objective: To improve reliability and endurance of semiconductor devices by means of heat exchange processes optimization of installations with evaporative air cooling. Methods: Design features analysis of cooling installations was applied. Results: The structural features of “a twophase thermal siphon” for power semiconductor devices were described. Experimental research of power blocks of semiconductor converter installations with “two-phase thermal siphon” coolers was conducted. The values of maximum permissible currents upon the application of possible button-type instrument configurations with such coolers were obtained. Practical importance: Application of “two-phase thermal siphon” evaporative air coolers will make it possible to improve weight-size parameters of converter installations.

scholarly journals Experimental study on dehumidification performance of liquid desiccant system with aqueous HCO2K solution

2021 ◽  
Author(s):  
Ijas Ahmed. M ◽  
◽  
Amulya Yatelly ◽  
Gangadhara Kiran Kumar L ◽  
◽  
...  
Keyword(s):  
Experimental Study ◽  
Flow Rate ◽  
Removal Rate ◽  
Heat Removal ◽  
Solution Flow Rate ◽  
Airflow Rate ◽  
Moisture Removal ◽  
Liquid Desiccant ◽  
Solution Flow ◽  
Removal Capacity

The liquid desiccant systems are one of the promising technologies in dehumidification applications. The experimental study on dehumidification performance of a counter flow structured packing liquid desiccant system is done with Aqueous HCO2K as working fluid. The HCO2K solution at different mass flow rate of air and solution is tested. The airflow rate is varied from 0.187 kg/s to 0.272 kg/s and the solution flow rate is varied from 0.053 to 0.115 kg/s. The output parameters, specific moisture change, moisture removal rate, dehumidification effectiveness and latent heat removal capacity varied in following ranges 3-4.2 g/kg of dry air, 2.4-3.1 kg/h, 0.12-0.21 and 1.7-2.1 kW respectively. Particularly when air flow rate increases from 0.187 kg/s to 0.272 kg/s the moisture removal performance improves about 11% whereas when the solution flow rate increases from 0.055 to 0.115 kg/s, improvement in moisture removal performance about 20%. The results imply that increase in solution flow rate always have the positive impact on dehumidification performance. The increase in airflow rate has the negative impact on specific moisture removal and effectiveness, but the impact is positive in case of the moisture removal rate and latent heat removal capacity. The Overall results show a promising dehumidification performance and further improvement is possible by incorporating a cooling system.

Thermodynamic Estimate of Minimal Dissipation for Heat Exchange System

2008 ◽  
Author(s):  
Andrei A. Akhremenkov ◽  
Anatoliy M. Tsirlin ◽  
Vladimir Kazakov
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
Heat Load ◽  
Point Of View ◽  
Exchange System ◽  
Heat Exchange System ◽  
Heat Exchange Surface ◽  
Minimal Dissipation ◽  
The Difference ◽  
Exchange Surface

In this paper we consider heat exchange system from point of view of Finite-time thermodynamics. At first time the novel estimate of the minimal entropy production in a general-type heat exchange system with given heat load and fixed heat exchange surface is derived. The corresponding optimal distribution of heat exchange surface and optimal contact temperatures are also obtained. It is proven that if a heat flow is proportional to the difference of contacting flows’ temperatures then dissipation in a multi-flow heat exchanger is minimal only if the ratio of contact temperatures of any two flows at any point inside heat exchanger is the same and the temperatures of all heating flows leaving exchanger are also the same. Our result based on those assumptions: 1. heat transfer law is linear (17); 2. summary exchange surface is given; 3. heat load is given; 4. input tempretures for all flows are given; 5. water equivalents for all flows are given.

Experimental Study of Bending Toughness on Hybrid Fiber Reinforced Concrete

2013 ◽  
Vol 327 ◽  
pp. 201-204
Author(s):  
Jin Song Shi ◽  
Bo Yuan ◽  
Da Zhang Wang ◽  
Zhe An Lu
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Fiber Reinforced Concrete ◽  
Bending Test ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Toughness Index ◽  
The Difference ◽  
Loading Methods ◽  
Index Value

In order to investigate the difference of current toughness index standards for fiber reinforced concrete, two main groups of specimens were made to take bending toughness test with the requirements of corresponded standards, loading methods and loading speeds, which are ASTM C1018 in America, ACI 544 and JSCE G552 in Japan. United with software Origin, the load-deflection curves gathered from bending test was calculated with relative standards. The results show that the calculated toughness index value with ASTM C1018-98 in America is more accurate with three grades but the requested deflection of testing is much longer than others while ACI 544 and JSCE G552 in Japan are quite the contrary.

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