Experimental comparison of the heat transfer of supercritical R134a in a micro-fin tube and a smooth tube

Wang, Dabiao; Tian, Ruifeng; Zhang, Yue; Li, Lanlan; Shi, Lin

doi:10.1016/j.ijheatmasstransfer.2018.10.052

Cited by 35 publications

(7 citation statements)

References 43 publications

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“…In addition to their experimental investigation, they also included numerical simulations based on two new field synergy analytical methods to further analyze the convective heat transfer behaviors. Wang et al [13] [14] measured the heat transfer in a smooth tube with an inner diameter of 10.3 mm and in a micro-finned tube with a hydraulic diameter of 7.85 mm, and compared these geometries to each other. For the micro-fin tube, different existing correlations were evaluated, but as none of them could accurately predict the heat transfer on the bottom of the tube, new correlations were developed for both the bottom and top Nusselt numbers.…”

Section: Introductionmentioning

confidence: 99%

“…The influence of pressure on the heat transfer coefficient is less straightforward compared to the influence of mass and heat flux. Wang et al [14] measured a decrease in heat transfer with increasing pressure for R134a both at the bottom and the top of the tube. However, when the fluid was heated above a certain bulk enthalpy, the opposite trend was noticed.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental Investigation of Near- and Supercritical Heat Transfer to R125 Flowing in a Horizontal Tube

Nieuwenhuyse

Meulemeester

Lecompte

et al. 2022

International Journal of Heat and Mass Transfer

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Near- and Supercritical Heat Transfer to R125 Flowing in a Horizontal Tube

Nieuwenhuyse

Meulemeester

Lecompte

et al. 2022

International Journal of Heat and Mass Transfer

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“…For correct components choice it mainly means the heat exchangers and the expander. As regarding the heat exchangers, a recent challenge is the direct recovery of exhaust gas, without secondary thermal circuit, and the most suitable choices are represented by shell and tube [36], plate-fin [37], and plate heat exchangers with the last ones selected because of their compact sizes and high heat transfer coefficient [38]. In smallscale and micro-scale ORC, the expander plays a key role in the system performance.…”

Section: Introductionmentioning

confidence: 99%

Performance analysis of a bio-diesel fired engine bottoming with micro-ORC

Falbo

Bova

2022

J. Phys.: Conf. Ser.

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The purpose of this work is to investigate the performance in terms of electric power and electric efficiency of a 11kW bio-diesel internal combustion engine (ICE) coupled with a micro Organic Rankine Cycle (ORC) both in design and off-design conditions. A zero dimensional (0D) thermodynamical engine model has been developed to predict the electric and thermal power with 100% biodiesel fuel (B100). B100 has been selected for the performance analysis of the integrated system due its lower environmental impact. For the ORC system, a subcritical thermodynamic model has been used with various working fluid (R245fa, R1233zd(E), R134a, R1234ze(E) and R1234ze(Z)). A plate heat exchanger (PHEX) has been adopted as evaporator of the organic cycle to directly recover the thermal power of the exhaust gas. Both models have been validated using experimental data from literature. Two different expander configurations, dynamic and volumetric, has been investigated. Model validations show good agreement with the experimental and literature data, respectively. Moreover, the results highlight that the micro-ORC could achieve a maximum electric efficiency of about 7% at full load with R1234ze(Z). Although at part load the dynamic expander show better performance, the volumetric expander has been selected for the system analysis due to its real suitability for small and micro scale ORC. Combined system results show a maximum enhancement of engine efficiency of about 5%, and better results, in terms of good compromise between electric efficiency and operating range width, has been shown for R1233zd(E). Furthermore, the direct coupling of the PHEX with the exhaust gases allows to have heat exchange evaporator areas below 2 m2 for all analysed fluids.

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“…Experimental data predicated (using the least square curve-fitting method) a modified Gnielinski's correlation which can give heat transfer coefficient within ±15% accuracy. Wang and Tian [24] conducted experimental investigations for supercritical fluid R134a flowing through micro-fin and smooth tube under horizontal position. These measurements under different mass fluxes, heat fluxes and pressures suggested that micro-fin tube resulted in higher heat transfer coefficient than that of smooth tube.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigations on Supercritical Heat Transfer Characteristics of Environmental Friendly Refrigerants

Ibrahim¹,

Hu²,

Jiang³

et al. 2021

IJCCE

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The heat transfer of supercritical fluids is a vastly growing field, specifically to find suitable alternatives to replace conventional R134a, which can be beneficial for climate change. Most of the experimental and numerical investigations have been conducted to explore supercritical water, carbon dioxide and R134a as heat transfer working fluids. Hydrofluoroolefin (HFO) and refrigerants blends have been considered the most environment-friendly refrigerants to replace Chlorofluorocarbons (CFCs), Hydrochlorofluoro-carbons (HCFCs) and Hydrofluorocarbons (HFCs). Their main advantage of zero Ozone Depletion Potential (ODP) and comparatively lower Global Warming Potential (GWP) have attracted growing amount of attention to mitigate environmental issues. This work adopts the computational method and takes the environmentally friendly refrigerants to investigate the heat transfer characteristics under widely used shear-stress transport (SST) model. A comprehensive comparison was performed at reduced pressure of 1.10 for supercritical fluids R515A, R1234ze(E) and R134a. The peaks of heat transfer coefficient occurred in the vicinity of pseudo critical temperature for all of these considered fluids; however, R134a resulted in higher heat transfer coefficient, Reynolds number and Prandtl number in comparison with R515A and R1234ze(E). The higher heat transfer coefficient of supercritical fluid R134a is owing to its thermophysical properties and the specific heat plays crucial role in the heat transfer of supercritical fluids. Owing to environmental issues, R515A can be a considerable replacement of R134a. R1234ze(E) is also promising alternative to R134a; however, safety issues should thoroughly concern its mild flammable characteristics.

show abstract

Experimental comparison of the heat transfer of supercritical R134a in a micro-fin tube and a smooth tube

Cited by 35 publications

References 43 publications

Experimental Investigation of Near- and Supercritical Heat Transfer to R125 Flowing in a Horizontal Tube

Experimental Investigation of Near- and Supercritical Heat Transfer to R125 Flowing in a Horizontal Tube

Performance analysis of a bio-diesel fired engine bottoming with micro-ORC

Numerical Investigations on Supercritical Heat Transfer Characteristics of Environmental Friendly Refrigerants

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