Flight test performance of a loop heat pipe—Focus on a long steady state with no apparent subcooling

1999 ◽  
Author(s):  
Michelle L. Parker ◽  
Bruce L. Drolen ◽  
P. S. Ayyaswamy
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Test Performance ◽  
Flight Test ◽  
Loop Heat Pipe

scholarly journals A Novel Analytical Modeling of a Loop Heat Pipe Employing Thin-Film Theory: Part II—Experimental Validation

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2403 ◽  
Author(s):  
Eui Guk Jung ◽  
Joon Hong Boo
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Film Theory ◽  
Design Parameters ◽  
Working Fluid ◽  
Coolant Temperature ◽  
Loop Heat Pipe ◽  
Analysis Model ◽  
Proposed Model ◽  
Flat Evaporator

Part I of this study introduced a mathematical model capable of predicting the steady-state performance of a loop heat pipe (LHP) with enhanced rationality and accuracy. Additionally, investigation of the effect of design parameters on the LHP thermal performance was also reported in Part I. The objective of Part II is to experimentally verify the utility of the steady-state analytical model proposed in Part I. To this end, an experimental device comprising a flat-evaporator LHP (FLHP) was designed and fabricated. Methanol was used as the working fluid, and stainless steel as the wall and tubing-system material. The capillary structure in the evaporator was made of polypropylene wick of porosity 47%. To provide vapor removal passages, axial grooves with inverted trapezoidal cross-section were machined at the inner wall of the flat evaporator. Both the evaporator and condenser components measure 40 × 50 mm (W × L). The inner diameters of the tubes constituting the liquid- and vapor-transport lines measure 2 mm and 4 mm, respectively, and the lengths of these lines are 0.5 m. The maximum input thermal load was 90 W in the horizontal alignment with a coolant temperature of 10 °C. Validity of the said steady-state analysis model was verified for both the flat and cylindrical evaporator LHP (CLHP) models in the light of experimental results. The observed difference in temperature values between the proposed model and experiment was less than 4% based on the absolute temperature. Correspondingly, a maximum error of 6% was observed with regard to thermal resistance. The proposed model is considered capable of providing more accurate performance prediction of an LHP.

scholarly journals Steady-state modeling and analysis of a loop heat pipe under gravity-assisted operation

2015 ◽  
Vol 83 ◽  
pp. 88-97 ◽  
Author(s):  
Lizhan Bai ◽  
Jinghui Guo ◽  
Guiping Lin ◽  
Jiang He ◽  
Dongsheng Wen
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Loop Heat Pipe ◽  
Modeling And Analysis

scholarly journals One-dimensional steady-state mathematical model of a novel loop heat pipe with liquid line capillary wick

2019 ◽  
Vol 38 (1) ◽  
pp. 253-273 ◽  
Author(s):  
Meng Fanxi ◽  
Quan Zhang ◽  
Sheng Du ◽  
Chang Yue ◽  
Xiaowei Ma
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Heat Pipe ◽  
Characteristic Point ◽  
Loop Heat Pipe ◽  
One Dimensional ◽  
Liquid Line ◽  
Working Medium ◽  
Compensation Chamber ◽  
Relative Errors

A novel loop heat pipe used for data center with a liquid line wick is designed, and its one-dimensional steady-state mathematical model is developed based on the energy and thermodynamic equilibrium of each component and the simulation results were validated by comparing with the experimental data in this work. The compensation chamber of the loop heat pipe was removed, and a section of capillary wick was added in the end of liquid line in order to reduce heat leakage and vapor backflow and increase working medium circulation power. The mathematical model of the novel loop heat pipe can be used to predict the operating temperature of each characteristic point with small relative errors of <13%. A parametric study of the steady-state performance characteristics including the effects of material, diameter, length, and porosity of liquid line wick are conducted, which provides a powerful basis for the design of novel loop heat pipe experiment.

Steady-State Operation of a Loop Heat Pipe: Network Thermofluid Model and Results

2003 ◽  
Author(s):  
Nima Atabaki ◽  
B. Rabi Baliga
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Horizontal Tube ◽  
Operating Conditions ◽  
Working Fluid ◽  
Loop Heat Pipe ◽  
Sintered Metal ◽  
Steady State Operation ◽  
Transport Line ◽  
Compensation Chamber

A network thermofluid model of a loop heat pipe (LHP) operating under steady-state conditions is presented. Attention is focused on a simple LHP, with one evaporator, a vapor transport line, a single condenser, a liquid transport line, and a compensation chamber. The evaporator is an internally grooved circular pipe, with a cylindrical wick installed on its inner surface. The wick is made of a sintered metal. The condenser is a horizontal tube covered with a high-thermal-conductivity sleeve, and the outer temperature of the sleeve is maintained at a constant sink temperature. Quasi one-dimensional mathematical models of the fluid flow and heat transfer in each of the elements of the LHP, and collectively of the entire LHP, are proposed and discussed. The working fluid considered in this work is ammonia, but the proposed model can work with any suitable fluid. Results pertaining to the LHP performance for a range of operating conditions are presented, compared (qualitatively) to corresponding results of an earlier experimental investigation in the literature, and discussed.

Mathematical Modeling of a Miniature Loop Heat Pipe With Two Evaporators and Two Condensers

2009 ◽  
Author(s):  
Jentung Ku ◽  
Triem Hoang ◽  
Tamara O’Connell
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Analytical Model ◽  
Computer Code ◽  
Loop Heat Pipe ◽  
Performance Tests ◽  
Thermal Vacuum ◽  
Start Up ◽  
Gravity Effects ◽  
Transient Thermal

A loop heat pipe (LHP) analytical model that simulates the steady state and transient thermal behaviors of LHPs with multiple evaporators and multiple condensers has recently been developed. It can be used as a stand-alone computer code or as a subroutine to general spacecraft thermal analyzers. Multi-evaporator and multi-condenser LHPs are more complex in their operation when compared to single-evaporator LHPs because of the thermal and fluid interactions among the evaporators, compensation chambers, and condensers. This analytical model has been used to simulate the thermal performance of a miniature loop heat pipe (MLHP) with two evaporators and two condensers in laboratory and thermal vacuum tests. In addition, the MLHP was tested in the laboratory under five different configurations where the relative elevations and tilts among loop components were varied so as to investigate the gravity effects on the loop performance and to verify the analytical model’s capability to predict such effects. The MLHP performance tests that were simulated included start-up, high power, heat transport limit, and heat load sharing between the two evaporators. In all tests that were modeled, the LHP analytical model accurately predicted the steady state and transient behaviors of the LHP. Furthermore, the model was run-time efficient and yielded stable solutions in all cases.

Mathematical modeling of steady-state operation of a loop heat pipe

2009 ◽  
Vol 29 (13) ◽  
pp. 2643-2654 ◽  
Author(s):  
Lizhan Bai ◽  
Guiping Lin ◽  
Hongxing Zhang ◽  
Dongsheng Wen
Keyword(s):  
Mathematical Modeling ◽  
Steady State ◽  
Heat Pipe ◽  
Loop Heat Pipe ◽  
Steady State Operation

Steady-State Operation of a Loop Heat Pipe With Analytical Prediction

2000 ◽  
Author(s):  
Heather Watson ◽  
Charlotte Gerhart ◽  
George Mulholland ◽  
Donald Gluck
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Air Force ◽  
Nickel Powder ◽  
Loop Heat Pipe ◽  
Analytical Prediction ◽  
Excellent Correlation ◽  
Horizontal Orientation ◽  
Steady State Operation ◽  
Air Force Research Laboratory

Abstract The steady-state performance of an 800W, sintered nickel powder wick, loop heat pipe (LHP) has been analyzed using a modified Dynatherm LHP Thermal Model. Results from characterization tests of this LHP performed at the Air Force Research Laboratory in Albuquerque, NM are used as the basis for comparison and discussion of results for the analytical model. The analytical predictions gave excellent correlation to the measured data for power levels ranging from 50 to 1500W at condenser chiller settings between −40°C and 20°C, with the LHP in a horizontal orientation.

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