scholarly journals Numerical Analysis on Enhancing Spray Performance of SCR Mixer Device and Heat Transfer Performance Based on Field Synergy Principle

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 786
Author(s):  
Jiedong Ye ◽  
Junshuai Lv ◽  
Dongli Tan ◽  
Zhiqiang Ai ◽  
Zhiqiang Feng
Keyword(s):  
Heat Transfer ◽  
Conversion Rate ◽  
Water Solution ◽  
Three Dimensional ◽  
Field Synergy ◽  
Field Synergy Principle ◽  
Spray System ◽  
Injection Methods ◽  
Wall Injection ◽  
Dimensional Simulation

The NH3 uniformity and conversion rate produced by the urea–water solution spray system is an essential factor affecting de-NOx efficiency. In this work, a three-dimensional simulation model was developed with the CFD software and was employed to investigate the effects of two typical injection methods (wall injection and center injection) and three distribution strategies (pre-mixer, post-mixer, pre-mixer, and post-mixer) of two typical mixers on the urea conversion rate and uniformity. The field synergy principle was employed to analyze the heat transfer of different mixer flow fields. The results show that the single mixer has instability in optimizing different injection positions due to different injection methods and injection positions. The dual-mixer is stable in the optimization of the flow field under different conditions. The conclusion of the field synergy theory of the single mixer accords with the simulation result. The Fc of the dual-mixer cases is low, but the NH3 conversion and uniformity index rate are also improved due to the increase in the residence time of UWS.

Heat Transfer Enhancement for Wake Zone Using Slit Pillar in Microchannel Heat Sinks

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Xiao Cheng ◽  
Huiying Wu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Electronic Device ◽  
Three Dimensional ◽  
Lower Surface ◽  
Heat Sinks ◽  
Transfer Performance ◽  
Microchannel Heat Sinks ◽  
Dimensional Simulation ◽  
Wake Zone

Abstract Pillar microchannel heat sinks have been widely used for chip cooling, while their overall heat transfer performance is restricted by the stagnation flow in pillar wake zone. In this work, a simple but effective method using slit microstructure modified on pillar was proposed to enhance wake zone heat transfer. It enables a special flow path for the incoming fluid that intensively disturbs the wake fluid. To validate the proposed method, a three-dimensional simulation was employed to study the laminar flow and heat transfer characteristics in the slit pillar microchannel. The pillar without slit design was also investigated for comparative analysis. Effects of slit angle (θ), height over diameter ratio (H/D), and blocking ratio (D/W) of a single pillar were systematically studied at the Reynolds numbers of 26–260. Results showed the case with θ = 0 deg always demonstrated lower surface temperature, higher Nusselt number and higher thermal performance index (TPI) compared to other cases with different slit angles at the same conditions. Furthermore, it was interesting to find that the slit configuration was not suitable for long pillar microchannel, but preferred for high blocking ratio pillar microchannel at present ranges (H/D ≤ 1, D/W ≤ 0.5). The slit pillar array microchannel was also explored and observed with improved overall heat transfer performance. The proposed slit microstructure well prevents the heat transfer deterioration in pillar wake zone, which is promisingly to be used for cooling performance improvement of electronic device.

Numerical Simulation and Optimization of Radial Heat Pipe Heat Exchanger Based on Field Synergy Principle

2013 ◽  
Vol 834-836 ◽  
pp. 1418-1422
Author(s):  
Qing Yun Liu ◽  
Fu Bing Tu ◽  
Sheng Yang Gao
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Transfer Coefficient ◽  
Heat Exchangers ◽  
Synergy Effect ◽  
Field Synergy ◽  
Field Synergy Principle ◽  
Radial Heat ◽  
The Heat Transfer Coefficient ◽  
Pipe Heat

This paper mainly explores the numerical simulation of flow and temperature fields in the shell-side of the radial heat pipe heat exchangers (HPHE), using CFD software-FLUENT. Field synergy principle is applied to analyze heat and mass transfer mechanism of heat exchangers; also, the influence of the variation of principle constructor parameters of heat exchangers on the field synergy effect and heat exchange performance has been studied. It has been found that better performance of heat exchangers is achieved with better field synergy effect; in the context of increasing transverse and longitudinal tube pitches within certain values of data, the heat transfer coefficient decreases as synergy angle increases. Variation of fin height has little effect on synergy angle, but it would decrease the heat transfer coefficient at unit pressure drop (k/Δp) as it increases; as fin pitch increases, the synergy angle first decreases and then grows, while k/Δp first increases and then decreases. The optimal ranges of heat exchanger structure parameters values were found.

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