摘要
以分布参数、一维均相模型为基础,建立了管壁两侧两相流体流动时的质量、动量、热量传递的耦合方程,在稳态工况下对两侧工质分别为R134a和R22的换热器模型进行了数值求解,采用"假想亚稳态法"解决数值计算过程中确定流动相态的准则方程式,得出了两相流动传热过程中各种参数的变化规律,并对其进行分析,提出了对双两相流换热器性能进行评价的主要参数。
The two sides of fluids in heat exchanger both undergo superheat state, vapor-liquid and subcool state, it has been seen in refrigeration technology and chemical engineering. The modeling based on one-dimension, distributed parameter, homogeneity has been proposed, it is concerned about continuity, momentum as well as energy equations. According to hypothesis of sub-steady state, the validation of phase-state about numerical calculation is accomplished. The simulation of R134a/R22 in two sides of heat exchanger has been solved, and the curves of parameters verses tube length L have been figured, the relations between them have been discussed. A new evaluation about this type of heat exchanger is proposed. With the results of simulation, some conclusion can be obtained, at first, a variety of parameters along with tube length at single phase flow state are different from that at two phase flow state, mainly as follows: 1. pressure P goes down fast at two phase than at single phase, but temperature T, the opposite; 2. convection heat transfer of two phase α is almost as five times as that of single phase, basic heat transfer takes place in the former; 3. because of the parameters, such as ,q=α_1ΔT_1=α_2ΔT_2,α_1, α_2, ΔT_1 and ΔT_2, are functions of tube length, then the evaluation method used in single phase against single phase, single phase against two phase, for example, heat transfer coefficient K and Logarithms mean temperature difference ΔT,is not adequate, otherwise, a new evaluation method has been developed, namely, heat flux q and average heat flux =∫~L_0q(z)dz/L; 4. is not only dependent on thermophysics property, operating condition, but also determined to phase coupling. In the end, it is efficient method to increase efficiency of heat exchanger, that the phase state between two sides of double two-phase flow phase is regulated to the same as soon as possible.
出处
《空气动力学学报》
EI
CSCD
北大核心
2004年第1期20-23,共4页
Acta Aerodynamica Sinica
基金
航空基金(02A52002).
