A Novel Electronics Cooling System Using Water Heat Pipes Under Freezing Conditions

2003 ◽  
Author(s):  
Osamu Suzuki ◽  
Atsuo Nishihara
Keyword(s):  
Prediction Model ◽  
Thermal Resistance ◽  
Ambient Temperature ◽  
Cooling System ◽  
Electronics Cooling ◽  
Heat Pipes ◽  
System Model ◽  
Cooling Performance ◽  
Temperature Range ◽  
Metal Block

A novel electronics cooling system that uses water heat pipes under an ambient temperature range from −30°C to 40°C has been developed. The system consists of several water heat pipes, air-cooled fins, and a metal block. The heat pipes are separated into two groups according to the thermal resistance of their fins. One set of heat pipes, which have fins with higher thermal resistance, operates under an ambient temperature range from −30°C to 40°C. The other set, which have lower resistance, operates from 0°C to 40°C. A prediction model based on the frozen-startup limitation of a single heat pipe was first devised and experimentally verified. Then, a prediction model for the whole-system was formulated according to the former model. The whole-system model was used to design a prototype cooling system, and it was confirmed that the prototype has a suitable cooling performance for an environmentally friendly electronics cooling system.

Modeling Size Effects of a Portable Two-Phase Electronics Cooling Loop With Different Refrigerants

2010 ◽  
Author(s):  
Tom Saenen ◽  
Martine Baelmans
Keyword(s):  
Size Effects ◽  
Cooling System ◽  
Electronics Cooling ◽  
Simple Algorithm ◽  
System Model ◽  
Two Phase ◽  
Component Mixture ◽  
Pressure Losses ◽  
Microchannel Cooling ◽  
Cooling Loop

A one dimensional dynamic system model is developed to accurately simulate a two-phase microchannel electronics cooling loop. This model is based on the single component mixture equations for mass, momentum and energy. These equations are solved numerically using a finite volume method in conjunction with the SIMPLE algorithm. To calculate the pressure losses and heat transfer state of the art empirical correlations are used. Furthermore size effects of a typical microchannel cooling system are investigated with the new model. Special attention is given to the accumulator size and its limitations for portable applications. A simple model to investigate the accumulator size effect on the loop is developed and compared to numerical results obtained from the system model. The influence of various loop parameters and possible improvements are also investigated. Finally the effect of using different coolants is studied.

A Design for Loop Thermosyphon Including Effect of Non-Condensable Gas

2011 ◽  
Author(s):  
Hiroyuki Toyoda ◽  
Tadakatsu Nakajima ◽  
Yoshihiro Kondo ◽  
Akio Idei ◽  
Shigemasa Sato
Keyword(s):  
Thermal Resistance ◽  
Ambient Temperature ◽  
Partial Pressure ◽  
Total Pressure ◽  
Air Cooling ◽  
Total Thermal Resistance ◽  
Cooling Performance ◽  
Design Information ◽  
Cooling Part

We have developed a loop thermosyphon for cooling electronics devices. Its cooling performance changes with the ambient temperature and amount of input heating. Especially it deteriorates with non-condensable gas (NCG) increase. NCG leakage of thermosyphon cannot detect below under 10−10 Pa-m3/s, though we have to design the thermosyphon considering these characteristics to provide guaranteed performance for 5–10 years. In this study, the effect of the amount of NCG in each component of a thermosyphon was measured while changing the amount of heater input, and the amount of NCG. As a result, we obtained some useful design information. The performance of air cooling part does not depend on the NCG amount in this case. The performance of evaporation part depends on the total pressure that includes the partial pressure of vapor and the partial pressure of NCG. The performance of condensation part is deteriorated strongly by NCG amount increase. Additionally, we expressed these performances as approximations. These expressions let us predict the total thermal resistance of this thermosyphon by the NCG amount and the input heating amount. Then, using the leakage of a thermosyphon and the amount of dissolved NCG in water, we predicted the amount of NCG that will be in the thermosyphon after 10 years. These results also let us predict the thermosyphon’s total thermal resistance after 10 years. Though there is a slight leakage on thermosyphon, using this technique, we are able to design a thermosyphon that is guaranteed the cooling performance for a long term.

scholarly journals New LED lamp design with heat pipes

2019 ◽  
pp. 34-42 ◽  
Author(s):  
D. V. Pekur ◽  
Yu. E. Nikolaenko ◽  
V. M. Sorokin
Keyword(s):  
Heat Exchanger ◽  
Thermal Resistance ◽  
Light Source ◽  
Cooling System ◽  
Heat Pipes ◽  
Ambient Air ◽  
Light Sources ◽  
Heat Conducting ◽  
Led Light ◽  
Semiconductor Crystals

The problem of climate change poses a challenge for humanity: it is necessary to reduce harmful emissions into the atmosphere, caused mainly by the burning of coal in thermal power plants. Partially, this problem can be solved by the use of energy-saving devices and equipment, including the replacement of traditional light sources with more efficient LEDs. This, however, causes the problem of ensuring normal thermal modes of the LEDs, since the more powerfull the LED is, the more heat is released in their semiconductor crystals, which leads to an increase in the temperature of the crystals and a decrease in the reliability of the device. This problem becomes especially urgent when using powerful multi-chip LED light sources, the so-called SOB matrices, whose power even now exceeds 500 W. This article presents a new design of a powerful LED lamp for indoor illumination of rooms with low ceilings. The heat from the LED is transferred via heat pipes to the heat exchanger rings looped around the light source. The heat exchanger rings are cooled by the natural convection of the surrounding air (at an ambient air temperature of 20°C). Computer simulation allowed evaluating the ability of the proposed cooling system to provide a normal thermal mode of the LED light source. The results on the computer simulations of the temperature field of light source`s cooling system showed that when the LED power is 300 W, the temperature of the light source`s base at the point where it is connected to the light source does not exceed 67.6°C. When the contact zone is covered with a 0.1 mm layer of heat-conducting paste (Arctiс Silver 5 type) with a thermal conductivity coefficient of 8.7 W/(m•°C), the temperature of the LED case reaches 70°C. If the thermal resistance of the LED light source is 0.1°C/W, then the temperature of its semiconductor crystals will be 100°C, well below the allowable temperature value of 150°C. The total thermal resistance of the cooling system is 0.159°C/W.

scholarly journals INFLUENCE OF THERMAL RESISTANCE OF AIR CONDENSER TUBES ON STEAM COOLING EFFICIENCY

2020 ◽  
Author(s):  
J. Jianguo ◽  
G. Varlamov ◽  
K. Romanova ◽  
L. Suxiang ◽  
L. Zhigang
Keyword(s):  
Mathematical Model ◽  
Thermal Resistance ◽  
Ambient Temperature ◽  
Cooling System ◽  
Steam Pressure ◽  
Operating Conditions ◽  
Air Cooling ◽  
Cooling Unit ◽  
Air Condenser ◽  
Working Bodies

The research is carried out using a mathematical model of conditions and features of condensation processes with the influence of changes in internal and external thermal resistances of working bodies, which occur during contamination of outside and inside metal pipes of heat exchange surfaces of air condenser. capacitor. Particular attention is paid to the selection, detailing and determination of more than twenty basic parameters that characterize the operation of the direct cooling unit of the condensing unit for the summer, the conditions of heat transfer processes between the working bodies taking into account the finned outer surface of elliptical condenser tubes. The results of experiments on the mathematical model are analyzed and the influence of the incoming air velocity and ambient temperature on the output steam pressure in the condenser direct air cooling system within the change of internal and external thermal resistances in the range 0-0.001(m2·K)/W due to cooling tube contamination is determined. air condenser steam turbine installation. Conditions, character and features of influence of thermal resistance of pollution in cooling tubes on steam pressure at an exit from them are defined, the basic factors defining steam pressure at an exit, necessity of the organization of control of thermal resistance of pollution in a pipe during unit operation at variable operating conditions and expediency is substantiated. conducting test studies of operating modes while taking into account the influence of thermal resistance of external and internal pollution on the thermal efficiency of the cooling unit. Studies have shown that at a fixed value of the heat load of the exhaust steam, the pressure of the steam outlet increases with increasing ambient temperature and decreasing the speed of the incoming air.

Optimized Thermoelectric Module-Heat Sink Assemblies for Precision Temperature Control

2011 ◽  
Author(s):  
Rui Zhang ◽  
David A. Brooks ◽  
Marc Hodes ◽  
Matthew van Lieshout ◽  
Vincent P. Manno
Keyword(s):  
Power Consumption ◽  
Thermal Resistance ◽  
Ambient Temperature ◽  
Thermoelectric Material ◽  
Temperature Control ◽  
Heat Sink ◽  
Heat Sinks ◽  
Temperature Range ◽  
Precision Temperature ◽  
Precision Temperature Control

Robust precision temperature control of photonics components is achieved by mounting them on thermoelectric modules (TEMs) which are in turn mounted on heat sinks. However, the power consumption of TEMs is high because high currents are driven through Bi2Te3-based semiconducting materials with high electrical resistivity and finite thermal conductivity. This problem is exacerbated when the ambient temperature surrounding a TEM varies in the usual configuration where the air-cooled heat sink a TEM is mounted to is of specified thermal resistance. Indeed, heat sinks of negligible and relatively high thermal resistances minimize TEM power consumption for sufficiently high and low ambient temperatures, respectively. Optimized TEM-heat sink assemblies reduce the severity of this problem. In the problem considered, total footprint of thermoelectric material in a TEM, thermoelectric material properties, heat load, component operating temperature, relevant component-side thermal resistances and ambient temperature range are prescribed. Provided is an algorithm to compute the unique combination of the height of the pellets in a TEM and the thermal resistance of the heat sink attached to it which minimizes the maximum power consumption of the TEM over the specified ambient temperature range. This optimization maximizes the fraction of the power budget in an optoelectronics circuit pack available for other uses. Implementation of the algorithm is demonstrated through an example for a typical set of conditions.

Performance of Thermoelectrics and Heat Pipes Refrigerator

2013 ◽  
Vol 388 ◽  
pp. 52-57 ◽  
Author(s):  
Ali A. Sungkar ◽  
Firman Ikhsan ◽  
M. Afin Faisol ◽  
Nandy Putra
Keyword(s):  
Ambient Temperature ◽  
Cooling System ◽  
Heat Pipes ◽  
Input Power ◽  
Cooling Load ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Cabin Temperature ◽  
Effective Performance ◽  
Vapor Compression Refrigeration

Most of refrigerators commonly use the conventional refrigeration system known as Vapor Compression Refrigeration System becoming a big issue lately due to ozone depleting substance it uses as the refrigerant. This paper will shows step by step of an experiment with the objective of constructing a refrigeration system based on thermoelectric which is reliable and compete able with the Vapor Compression Refrigeration System. The designing of this refrigeration system shows attention to the environment that is combined with the knowledge so the environmental friendly technology can be applied. The performance of thermoelectric refrigerator was conducted under variation of input power (40W, 72W, and 120W) and operated in ambient temperature and cooling load of water 1000mL to investigate the characteristic of system, the performance, and also the COP. The COP is decrease by increasing of cooling load, QL. The best actual COP is 0.182 reached when the refrigerator operated at input power 40W. The result, it shows that decreasing of ambient temperature affects the decreasing of cabin temperature. Thermoelectric and heat pipe refrigerator cooling system can reach cabin temperature with power 120Watt (8.73A, 14V) produces temperature of compartment is 10.63°C indicates effective performance work-based thermoelectric applications.

scholarly journals A Numerical Analysis of the Cooling Performance of a Hybrid Personal Cooling System (HPCS): Effects of Ambient Temperature and Relative Humidity

2020 ◽  
Vol 17 (14) ◽  
pp. 4995
Author(s):  
Pengjun Xu ◽  
Zhanxiao Kang ◽  
Faming Wang ◽  
Udayraj Udayraj
Keyword(s):  
Numerical Analysis ◽  
Relative Humidity ◽  
Ambient Temperature ◽  
Thermal Performance ◽  
Environmental Temperature ◽  
Cooling System ◽  
Cooling Performance ◽  
Hot Environment ◽  
Four Levels ◽  
Personal Cooling

Hybrid personal cooling systems (HPCS) incorporated with ventilation fans and phase change materials (PCMs) have shown its superior capability for mitigating workers’ heat strain while performing heavy labor work in hot environments. In a previous study, the effects of thermal resistance of insulation pads, and latent heat and melting temperature of PCMs on the HPCS’s thermal performance have been investigated. In addition to the aforementioned factors, environmental conditions, i.e., ambient temperature and relative humidity, also significantly affect the thermal performance of the HPCS. In this paper, a numerical parametric study was performed to investigate the effects of the environmental temperature and relative humidity (RH) on the thermal management of the HPCS. Five levels of air temperature under RH = 50% (i.e., 32, 34, 36, 38 and 40 °C) and four levels of environmental RH at two ambient temperatures of 36 and 40 °C were selected (i.e., RH = 30, 50, 70 and 90%) for the numerical analysis. Results show that high environmental temperatures could accelerate the PCM melting process and thereby weaken the cooling performance of HPCS. In the moderately hot environment (36 °C), HPCS presented good cooling performance with the maximum core temperature at around 37.5 °C during excise when the ambient RH ≤ 70%, whereas good cooling performance could be only seen under RH ≤ 50% in the extremely hot environment (40 °C). Thus, it may be concluded that the maximum environmental RH under which the HPCS exhibiting good cooling performance decreases with an increase in the environmental temperature.

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