Boiling heat transfer and two-phase pressure drops within compact plate heat exchangers: Experiments and flow visualizations

Abstract

Infrared (IR) thermography was used to measure the local heat transfer coefficients within two plate heat exchanger geometries. The chevron patterns were machined into polycarbonate and IR transparent calcium fluoride plates, both of which were electrically heated using flexible film heaters at heat fluxes up to 0.8 W cm-2. The test fluid was a refrigerant (HFE7100) at mass fluxes between 25 and 100 kg m-2 s-1 , and qualities from 0 to 0.9. The apparatus and data reduction technique were validated by comparing the single-phase heat transfer and pressure drop data against the prediction methods from the literature. Adiabatic flow visualizations were conducted to link the flow patterns with the observed heat transfer. The frictional pressure gradient and heat transfer coefficient were compared with available correlations. It was shown that the heat transfer coefficient and the frictional pressure gradient increased with mass flux and quality. The comparison indicated the need for new prediction methods for predicting the local thermalhydraulic performance over a wide range of operating conditions.

Flow boiling heat transfer and pressure drop characteristics of R134a, R1234yf and R1234ze in a plate heat exchanger for organic Rankine cycle units

“…Unlike the experimental results in Refs. [8][9][10][11][12], a nucleate boiling-dominant process was found by Huang et al [13] when outlet vapour quality xout = 0.4-1. The authors performed an experimental investigation of the heat transfer and pressure drop of R134a and R507A with three industrial PHEs.…”

“…In the flow boiling process, two main heat transfer mechanisms exist, which are named nucleate and convective boiling. A common phenomenon has been presented in some research [8][9][10][11][12], that is, nucleate boiling and convective boiling are predominant at low and high vapour qualities, respectively. With the further increase of vapour quality, the flow enters into the dryout regime.…”

“…This phenomenon is different from those reported in Refs. [8][9][10][11][12], and it is attributed to the fact that water has very different thermophysical properties than those of refrigerants. Overall, the issues surrounding which mechanism is predominant for the review for flow boiling and frictional pressure gradients in PHEs [3], the authors claim that compared with single-phase flow inside PHEs which has been widely studied, two-phase flow and heat transfer were studied less.…”

An effective krill herd based optimal NN for parameter evaluation in Shell-And-Tube heat exchangers

“…In recent years, numerous approaches for the performance design and optimization of practical thermodynamic cycles have been explored and applied in engineering [14] and also they developed a set of correlations for two-phase evaporators with a focus on ammonia as a working fluid that included the effect of chevron angle on the thermal and hydraulic performance [15]. Many studies on the configuration of shell and tube heat exchangers can be carried out.…”

Critical heat flux enhancement of HFE-7100 flow boiling in a minichannel heat sink with saw-tooth structures

“…8 HFE-7100 was also employed to investigate the CHF and post-CHF characteristics during the falling jets on the surface with localized electrostatic fields 9 or the heat transfer enhancement of the pool boiling on the nanoparticle-coated surface. 10 In recent years, many approaches have been reported to improve the boiling heat transfer in the microchannel.…”