Innovative concept of splitting water flow rate of cross flow heat exchangers as a solution for reduction of non-uniformity effect – Thermal modelling and feasibility analysis

Abstract

The water flow rate of water-air cross-flow Heat Exchangers (HXs) is split into various smaller flow rates in this research work, which circulates into several smaller HXs that are put together. In fact, as the non-uniformities in the airflow velocity distributions increase, the thermal performance declines. These non-uniformities, especially in automotive applications, are represented by velocity magnitudes on a part of the HX front area and zero velocities on the remaining part. The innovative idea and the originality of the present study consists on dividing the water flow rates into various passageways as they reach a water-flow HX, where each passage is associated with several smaller HXs. In relation to the air flow, the smaller HXs are sequentially combined. The advantage of such splitting leads to keeping parts of the area of the initial HX from being subjected to low convection heat transfer with zero or negligible velocities and subsequently allows for an increase in the thermal performance globally. Moreover, the dividing idea enables faster but hotter airflow to be applied to each of the individual HXs. Computations for double-split HX utilizing a developed computational code are used to demonstrate the viability of this design. A traditional cross-flow water-air HX's thermal performance can be improved by up to 26.2 % using the novel idea, it has been demonstrated.