Experimental Investigation on Heat Transfer Mechanism of Air-Blast-Spray-Cooling System with a Two-Phase Ejector Loop for Aeronautical Application

• Main Authors: Jia-Xin Li, Yun-Ze Li, Ben-Yuan Cai, En-Hui Li
• Format: Article
• Language: English
• Published: MDPI AG 2019-10-01
• Series: Energies
• Subjects: spray cooling; ground-based test setup; two-phase ejector; aeronautical application; empirical experimental correlation
• Online Access: https://www.mdpi.com/1996-1073/12/20/3963

This paper presents an air-oriented spray cooling system (SCS) integrated with a two-phase ejector for the thermal management system. Considering its aeronautical application, the spray nozzle in the SCS is an air-blast one. Heat transfer performance (HTP) of air-water spray cooling was studied experimentally on the basis of the ground-based test. Factors including pressure difference between water-inlet-pressure (WIP) and spray cavity one (PDWIC) and the spray volumetric flow rate (SVFR) were investigated and discussed. Under a constant operating condition, the cooling capacity can be promoted by the growth factors of the PDWIC and SVFR with the values from 51.90 kPa to 235.35 kPa and 3.91 <inline-formula> <math display="inline"> <semantics> <mrow> <mi mathvariant="normal">L</mi> <mo>&#8901;</mo> <msup> <mi mathvariant="normal">h</mi> <mrow> <mrow> <mo>&#8722;</mo> <mn>1</mn> </mrow> </mrow> </msup> </mrow> </semantics> </math> </inline-formula> to 14.53 <inline-formula> <math display="inline"> <semantics> <mrow> <mi mathvariant="normal">L</mi> <mo>&#8901;</mo> <msup> <mi mathvariant="normal">h</mi> <mrow> <mrow> <mo>&#8722;</mo> <mn>1</mn> </mrow> </mrow> </msup> </mrow> </semantics> </math> </inline-formula>, respectively. Under the same heating power, HTP is proportional to the two dimensionless parameters Reynolds number and Weber number due to the growth of droplet-impacting velocity and droplet size as the increasing of PDWIC or SVFR. Additionally, compared with the factor of the droplet size, the HTP is more sensitive to the variation in the droplet-impacting velocity. Based on the experimental data, an empirical experimental correlation for the prediction of the dimensionless parameter Nusselt number in the non-boiling region with the relative error of only <inline-formula> <math display="inline"> <semantics> <mrow> <mo>&#177;</mo> <mn>10</mn> <mo>%</mo> </mrow> </semantics> </math> </inline-formula> was obtained based on the least square method.