Thermal Design of a Sealed Air Cooling Local Environment Control System for Precision Instruments In-Vehicle

2011 ◽  
Vol 120 ◽  
pp. 258-262
Author(s):  
Hong Cai Li ◽  
Fei Fan Chen ◽  
Yong Gui Dong
Keyword(s):  
Control System ◽  
Flow Rate ◽  
Local Environment ◽  
Thermal Design ◽  
Heat Transfer Analysis ◽  
Heat Radiation ◽  
Air Cooling ◽  
Heat Flow Rate ◽  
Electrical Analogy ◽  
Environment Control

Local environment control system (LECS) has been widely used in many areas as the necessary guarantee for most precision instruments. A sealed air cooling constant temperature box with dual-chamber structure that can provide constant working condition for precision instruments in-vehicle was developed. According to the heat transfer analysis of the double plate-fins heatsink, the heat radiation area and dimensions were determined based on electrical analogy. The air flow rate and temperature distribution of the system in heat steady-state was simulated by CFD software, and the results are consistent with that of experimental test. In different conditions, the thermal test results indicate that when the heat flow rate in the inner chamber is about 170 W, the temperature difference between inner chamber and environment is no more than 6.5 °C. The thermal design and test methods can be as the reference for the design of other precision instruments in-vehicle.

Thermal Test of a Sealed Air Cooling Local Environment Control Apparatus for Precision Instruments

2012 ◽  
Vol 468-471 ◽  
pp. 1099-1103
Author(s):  
Hong Cai Li ◽  
Fei Fan Chen ◽  
Yong Gui Dong
Keyword(s):  
Thermal Conductance ◽  
Local Environment ◽  
Test Method ◽  
Working Environment ◽  
Air Cooling ◽  
Electrical Analogy ◽  
Environment Control ◽  
Relative Errors ◽  
Control Apparatus ◽  
Transfer Properties

A sealed air cooling local environment control apparatus that can provide constant working environment for precision instruments has been developed. Based on electrical analogy, the thermal network model has been derived, and the parameters of thermal conductance and capacitance in the model were measured in different test conditions. The obtained maximum relative errors between the measured values and the theoretical values are in the range of 0.6% to 6%, which indicates that the proposed theoretical model and the test method are feasible. The obtained parametes can help to understand the heat transfer properties of the apparatus, and the methods can be also as the reference for the test and rapid commissioning of other local environment control apparatus.

Computational fluid dynamics investigation of heat-exchangers for various air-cooling systems in poultry houses

2020 ◽  
Vol 97 (1) ◽  
pp. 125-134
Author(s):  
V.I. Trokhaniak ◽  
◽  
I.L. Rogovskii ◽  
L.L. Titova ◽  
P.S. Popyk ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Control System ◽  
Heat Exchangers ◽  
Controlled Environment ◽  
Air Cooling ◽  
Poultry Houses ◽  
Computational Fluid Dynamics Analysis ◽  
Environment Control ◽  
Ventilation Systems

The increase in the productivity of poultry plants is connected with the necessity to create the optimal controlled environment in poultry houses. This problem is of prime importance due to the decrease of poultry plant productivity caused by the imperfection of the existing controlled environment systems. The paper presents the improved environment control system in a poultry house. The processes of heat- and mass-exchange in the developed heat-exchangers for various ventilation systems have been investigated. Computational Fluid Dynamics analysis of the heat-exchangers of two various designs for tunnel and side ventilation systems has been carried out. The fields of velocities, temperatures and pressures in the channels under study have been obtained. The conditions of a hydrodynamic flow in the channels have been analyzed. The intensity of heattransfer between a hot heat carrier and a cold one through their separating wall has been estimated. The most efficient heat-exchanging apparatus has been determined and the application potential of such a design has been substantiated. The aim of the research is the development and numerical modelling of a shell-and-tube heat-exchanger of a new design as an element of environment control system used in various types of ventilations systems in summer seasons.

Thermal Analysis and Modeling of LED Arrays for Automotive Headlamp

2007 ◽  
Author(s):  
Sun Ho Jang ◽  
Moo Whan Shin
Keyword(s):  
Thermal Analysis ◽  
Cooling System ◽  
Thermal Design ◽  
Junction Temperature ◽  
Heat Transfer Analysis ◽  
Air Cooling ◽  
Fluid Field ◽  
Led Array ◽  
Air Cooling System ◽  
Led Arrays

In this paper we report the thermal performance of LED head lamp module and the cooling system. The precise fluid field modeling and heat transfer analysis using a CFD (Computational Fluid Dynamics) were performed according to the practical working conditions for the headlamp. The junction temperatures of LEDs were found to decrease by using the air cooling system and thus improved the heat dissipating capability of the LED array. The junction temperature of the LED array was decreased from 70.6 °C to 30.25 °C when the circulating speed of the air increased from 0 km/h to 120 km/h. And the temperature decrease of 2∼4 °C was obtained by using fins. By the thermal analysis, a new thermal design was obtained for the cooling system of LED arrays for the headlamps. Thus the reliability of the headlamp with LED arrays can be improved with a good cooling system.

Relationships Between Supply Flow Rate of Small Cooling Fans and Pressure Drop Characteristics in Electronic Enclosure

2013 ◽  
Author(s):  
Takashi Fukue ◽  
Tomoyuki Hatakeyama ◽  
Masaru Ishizuka ◽  
Koichi Hirose ◽  
Katsuhiro Koizumi
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Flow Resistance ◽  
High Density ◽  
Thermal Design ◽  
Air Cooling ◽  
Operating Pressure ◽  
Resistance Curve ◽  
Cooling Fans ◽  
High Density Packaging

This study describes a prediction method of a supply flow rate of axial cooling fans mounted in high-density packaging electronic equipment. The performance of an air-cooling fan is defined by its P – Q (pressure difference – flow rate) curve. Generally the operating point of a fan, which is the operating pressure and the flow rate in equipment, is the point of intersection of a P – Q curve and a flow resistance curve. Recently, some researchers reported that catalogue P – Q curves have not necessarily been able to predict a correct supply flow rate in thermal design of high-density packaging equipment. Our study aims to improve prediction accuracy of the supply flow rate. In this report, a relationship between the P – Q curve and a pressure drop characteristic in a fan-mounted enclosure was investigated. A test enclosure which includes an obstruction was mounted in front of a test fan and the supply flow rate of the fan was measured while changing the obstruction. Additionally the flow resistance curves in the test enclosure were measured and the relationship among the supply flow rate, the P – Q curve and the flow resistance curve was investigated. It is found that the correct supply flow rate can be obtained by using the flow resistance from the enclosure inlet through the fan outlet and the revised P – Q curve which is made compensation for the pressure drop at the inlet and the outlet of the fan.

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 Effect of Cooling Flow on the Operation of a Hot Rotor-Gas Foil Bearing System

2012 ◽  
Author(s):  
Keun Ryu ◽  
Luis San Andrés
Keyword(s):  
Thermal Management ◽  
Flow Rate ◽  
System Integration ◽  
Damping Ratio ◽  
Temperature Drop ◽  
Test System ◽  
The Body ◽  
Air Cooling ◽  
Cooling Flow ◽  
Management Procedures

Gas foil bearings (GFBs) operating at high temperature rely on thermal management procedures that supply needed cooling flow streams to keep the bearing and rotor from overheating. Poor thermal management not only makes systems inefficient and costly to operate but could also cause bearing seizure and premature system destruction. This paper presents comprehensive measurements of bearing temperatures and shaft dynamics conducted on a hollow rotor supported on two first generation GFBs. The hollow rotor (1.36 kg, 36.51 mm OD and 17.9 mm ID) is heated from inside to reach an outer surface temperature of 120°C. Experiments are conducted with rotor speeds to 30 krpm and with forced streams of air cooling the bearings and rotor. Air pressurization in an enclosure at the rotor mid span forces cooling air through the test GFBs. The cooling effect of the forced external flows is most distinct when the rotor is hottest and operating at the highest speed. The temperature drop per unit cooling flow rate significantly decreases as the cooling flow rate increases. Further measurements at thermal steady state conditions and at constant rotor speeds show that the cooling flows do not affect the amplitude and frequency contents of the rotor motions. Other tests while the rotor decelerates from 30 krpm to rest show that the test system (rigid-mode) critical speeds and modal damping ratio remain nearly invariant for operation with increasing rotor temperatures and with increasing cooling flow rates. Computational model predictions reproduce the test data with accuracy. The work adds to the body of knowledge on GFB performance and operation and provides empirically derived guidance for successful rotor-GFB system integration.

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