An experimental investigation on heat transfer coefficient is presented from three horizontal tubes in a vertical array in a duct for 500<ReD<6000. A mass transfer measuring technique based on psychrometry chart is used to determine heat transfer coefficient. The diameter of the tubes is 11 mm each spaced 40 mm apart and in-line pitch ratio varies in the range 0.055<D/W<0.22. The experimenta...

This paper develops a semi-empirical expression for heat transfer in round tube plain fin heat exchangers that have relatively large fin pitch. Empirical heat transfer correlations currently available in the public domain are necessarily limited in their range of applicability, and their functional forms are generally not designed to converge to well-known physical results, for example when par...

Microchannel heat exchangers (MCHXs) are now widely used in the HVAC&R industry. Similar to tube-fin heat exchangers used mainly in the indoor units, the innovative variable geometry microchannel heat exchanger will further reduce its compact size and enhance its performance. Variable geometry refers to a heat exchanger with different tube and fin surfaces within the same core with one or more ...

In this study, by using a multi-objective optimization technique, the optimal design points of forced convective heat transfer in tubular arrangements were predicted upon the size, pitch and geometric configurations of a tube bank. In this way, the main concern of the study is focused on calculating the most favorable geometric characters which may gain to a maximum heat exchange as well as a m...

Validation simulations are presented for turbulent flow in a staggered tube bank, geometry similar to the lower plenum of a gas-cooled high temperature reactor. Steady 2D RANS results are compared to unsteady 2D RANS results and experiment. The unsteady calculations account for the fact that nonturbulent fluctuations (due to vortex-shedding) are present in the flow. The unsteady computations ar...

This work presents procedures to compute the heat transfer coefficient when downwards flowing pure vapours (or azeotropic mixtures) condense on horizontal integral-fin tubes. At first, single tubes are considered, and the suggested procedure takes shear, gravity and surface tension force into account. The method is compared with a vast data bank demostrating a sound concordance. The second part...