Numerical model and effectiveness correlations for a run-around heat recovery system with combined counter and cross flow exchangers
Numerical model and effectiveness correlations for a run-around heat recovery system with combined counter and cross flow exchangers
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DOI：
10.1016/j.ijheatmasstransfer.2009.07.020
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发表时间：
2009-12
影响因子：
5.2
通讯作者：
Ali M. Vali;C. Simonson;R. Besant;G. I. Mahmood
中科院分区：
文献类型：
--
作者：
Ali M. Vali;C. Simonson;R. Besant;G. I. Mahmood
建立了一个二维稳态数值模型，研究了具有两个交换器的循环式热回收系统的传热，每个交换器在平行板或膜之间具有反向和交叉流动的组合。采用有限差分法求解了稳态连续方程、动量方程和传热方程。每个逆流/交叉流热交换器和整个循环系统的有效性的模拟值用于建立有效性相关性，该相关性在单个热交换器和整个系统的模拟有效性的±2%范围内一致。结果表明，这种新型循环换热器（RAHE）的效率介于具有两个交叉流换热器或两个逆流换热器的类似循环系统的效率之间。对于给定的交换器总表面积，具有较小的交换器长径比和相对较小的溶液流入口和出口长度的交换器可获得最高的总体显效率。
A two-dimensional steady-state numerical model is developed to study the heat transfer in a run-around heat recovery system with two exchangers each with a combination of counter and cross (counter/cross) flow between parallel plates or membranes. A finite difference method is used to solve the steady-state equations of continuity, momentum and heat transfer. The simulated values for the effectiveness of each counter/cross flow heat exchanger and the overall run-around system are used to develop effectiveness correlations which agree within ±2% of the simulated effectiveness of individual heat exchangers and overall system. It is shown that the effectiveness of this new run-around heat exchanger (RAHE) falls between the effectiveness of similar run-around systems with either two cross-flow exchangers or two counter-flow exchangers. For a given total surface area of the exchangers, the highest overall sensible effectiveness is achieved with exchangers which have a small exchanger aspect ratio and relatively small solution flow inlet and outlet lengths.