Continuous vs. pulsating flow boiling. Part 2: Statistical comparison using response surface methodology

Martin Ryhl Kærn, Brian Elmegaard, Knud Erik Meyer, Björn Palm, Jørgen Holst

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Abstract

Response surface methodology is used to investigate an active method for flow boiling heat transfer enhancement by means of fluid flow pulsation. The flow pulsations are introduced by a flow modulating expansion device and compared with the baseline continuous flow provided by a stepper-motor expansion valve. Two experimental designs (data point sets) are generated using a modified Central Composite Design for each valve and their response surfaces are compared using the quadratic model. Statistical information on the significant model terms are used to clarify whether the effect of fluid flow pulsations is statistically significant in terms of the time-averaged flow boiling heat transfer coefficient. The cycle time range from 1 s to 9 s for the pulsations. The results show that the effect of fluid flow pulsations is statistically significant, disregarding the lowest heat flux measurements. The response surface comparison reveals that the flow pulsations improves the time-averaged heat transfer coefficient by as much as 10 % at the smallest cycle time compared with continuous flow. On the other hand, at highest cycle time and heat flux, the reduction may be as much as 20 % due to significant dry-out when the valve is closed. These values are higher than reported in part 1 of the paper, but evaluated more consistently at equal heat flux using the response surfaces.
Original languageEnglish
Title of host publicationProceedings of the 16th International Refrigeration and Air Conditioning Conference
PublisherRay W. Herrick Laboratories
Publication date2016
Pages1319-1327
Article number2514
ISBN (Electronic)978-1-5108-2873-5
Publication statusPublished - 2016
Event16th International Refrigeration and Air Conditioning Conference - Purdue University, West Lafayette, IN, United States
Duration: 11 Jul 201614 Jul 2016
https://engineering.purdue.edu/Herrick/Events/Conferences

Conference

Conference16th International Refrigeration and Air Conditioning Conference
LocationPurdue University
CountryUnited States
CityWest Lafayette, IN
Period11/07/201614/07/2016
Internet address

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