A modified efficiency-NTU method (m-ε-NTU) for calculating air coolers in dehumidifying or frost conditions. Part I

Abstract

In this part of the article, a literary review of the methods of stationary calculations of air coolers operating in dehumidifying or frost conditions is carried out. The approaches used at the moment are reviewed, namely: dehumidification coefficient method; logarithmic enthalpy difference method (LMED); equivalent dry-bulb temperature method (EDT); as well as -NTU method (efficiency number of heat transfer units) for calculating counterflow chilled water coils. Their main differences are shown and the key expressions used in them are given. A comparison of the advantages and disadvantages of the considered methods showed the rationality of using -NTU approach due to the possibility of its application for both design and verification calculations of heat exchangers. Since the classical -NTU method is not directly applicable to dehumidifying or frost conditions, it becomes necessary to adapt it to the calculations of air coolers of all types (both counterflow and parallel-flow air coolers without phase transition of the cooling fluid, and for cases with its phase transition) to correctly describe the effect of the above processes on heat exchange.