Development of new finned tube heat exchanger: Innovative tube-bank design and thermohydraulic performance

Abstract

Three-dimensional numerical simulations are successfully carried out on thermo-hydraulic characteristics of a new plain fin-and-elliptical tube (PFET) heat exchanger with innovative types of tube-banks, namely—a slotted elliptical tube-bank (SETB) (Case B and Case C) and a slotted annular elliptical tube-bank (SAETB) (Case D and Case E). The new PFET heat exchanger contains elliptical cross-sectioned tubes that create narrow slots oriented in the streamwise or/and spanwise direction. The investigation on the effects of different shape tube-banks on the air-side heat transfer and fluid flow characteristics in the new PFET heat exchanger was performed using the ANSYS CFX® package. The objectives of this investigation are to determine an optimal staggered tube-bank configuration for augmenting heat transfer rates with minimal pressure drop penalties, and compare the results against traditional non-slotted elliptical tube-bank heat exchangers. The averaged heat transfer rate of the SETB/SAETB heat exchanger is more than 15% greater than that of the traditional non-slotted elliptical tube heat exchanger. The overall performance evaluation criteria, estimated in terms of the area goodness factor and volume goodness factor for enhanced cases (SETBs/SAETBs), were higher than there found by a non-slotted elliptical tube-bank case. Overall, the computational results showed that the Case D causes an appreciable increase of the heat transfer rate without a pressure drop penalty.