HEAT TRANSFER CHARACTERISTICS OF THE MULTITHREADED HELICALLY COILED TUBE GENERATOR USED IN THE ABSORPTION-COMPRESSION HYBRID REFRIGERATION CYCLE

Abstract

The generator is a key device in the absorption−compression hybrid refrigeration cycle (ACH-RC). Multithreaded helically coiled tubes were used in the generator as heat exchanging elements. The heat transfer characteristic of the coil generator has been inadequately researched because of the complicated character of heat transfer between the gases from engines and the working fluid in the helically coiled tube generator. This article attempts at discussing this by numerical simulation. First, the construction parameters of the coil generator were confirmed by CFD simulation under the limited resistance to flowing gases. Then, the heat transfer models of the coil generator were developed based on some simplifications and assumptions. The heat transfer characteristic of the coil generator was simulated by difference calculus. The results show that the heat transfer area, efficient heat exchange height of the coil generator are 2.24 m2 and 0.784 m, respectively. While the engine output reaches 180 kW, the heat transfer load of the coil generator can meet the requirement of 58.68 kW which is the load for the cooling capacity provided fully by the absorption refrigeration subcycle (ARSC). The pressure drop in the gas flowing through the coil generator is 1.65 kPa.