Using a spiral fin to replace a wavy fin in the condenser of an air conditioner

An experimental and numerical investigation of an L-footed spiral fin's thermal performance for replacement of wavy fins used in condensers is presented. This condenser is used for air conditioners with a capacity of 2.64 kW–3.52 kW (9000–12,000 BTU/hr). Eight spiral fins with various fin pitches and fin diameters are studied. Each spiral fin is designed to have an area that is equal to that of a baseline wavy fin. The investigation found that the heat transfer coefficient and pressure drop obtained with the wavy fin are greater than those obtained with a spiral fin. Moreover, the spiral fin gives a performance index or “goodness factor” that is about 0.2–11.9 % greater than that of a wavy fin

Absorption refrigeration system using engine exhaust gas as an energy source

A single-effect absorption refrigeration system that uses LiBr-water solution and engine exhaust gas is investigated. The generator is a spiral fin-and-tube heat exchanger, while the condenser, evaporator, and absorber are shell and coil heat exchangers. Experiments are conducted at engine speeds of 1000, 1200, 1400, and 1600 rpm; expansion valve opening percentages of 54.5%, 72.7%, and 90.9% at the separator outlet and 3.41%, 4.55%, and 5.68% at the condenser outlet; refrigerant temperatures at the condenser outlet of 25, 30, and 35 °C; and LiBr-water solution flow rates of 0.35 and 0.7 LPM. The results show that the system could work with an engine speed of 1200–1400 rpm. The cooling load and coefficient of performance (COP) increase with increasing engine speed. The highest COP of 0.275 is reached at an engine speed of 1400 rpm, opening percentage of 72.7% at the separator outlet and 4.55% at the condenser outlet, water temperature of 25 °C at the condenser outlet, and LiBr-water flow rate of 0.7 LPM. The decreased refrigerant temperature at the condenser outlet helps to increase both cooling load and COP. The increase of the LiBr-water solution flow rate helps to increase cooling load but decrease COP. Keywords: Absorption refrigeration, LiBr-water solution, Exhaust gas, CO