Experimental and Numerical Study of Double-Pipe Evaporators Designed for CO2 Transcritical Systems

Processes

Shuying Ning¹  Junlan Yang¹ 

[1] School of Energy and Safety Engineering, Tianjin Chengjian University, Tianjin 300384, China;

关键词: CO₂;    heat transfer;    double-pipe evaporator;    experimental study;    simulation;   

DOI  :  10.3390/pr7080547

来源: DOAJ

【 摘 要 】

The performance of a CO₂ double-pipe evaporator was studied through experiments and a simulation model that was established by the steady-state distribution parameter method and experimentally verified while using a CO₂ transcritical water‒water heat pump system. The effects of different operating parameters on heat transfer performance were studied over a range of evaporation temperatures (−5 to 5 °C), mass velocity (100‒600 kg/m²s), and heat flux (5000‒15,000 W/m²). It was found that the dryout quality increased at a small evaporation temperature, a large mass velocity, and a small heat flux. The simulation yield means relative error (RE) of heat transfer for the evaporation temperature and that of the CO₂ pressure drop for the chilled water inlet temperature were 5.21% and 3.78%, respectively. The effect of tube diameter on the performance of CO₂ double-pipe evaporator is probed through simulations. At the same time, this paper defines a parameter $\mathsf{\alpha }$ , which is the proportion of the pre-dryout region to the whole heat transfer region. A larger $\mathsf{\alpha }$ value is desirable. A further theoretical basis is provided for designing an efficient and compact CO₂ evaporator.

【 授权许可】

Unknown