Performance Evaluation of a Drying System for Isan Musical Instrument Raw Materials Using Waste Heat from Air Conditioners: A Case Study of Ban Tha Ruea, Na Wa District, Nakhon Phanom Province.

Abstract

This research investigates the technical feasibility and evaluates the performance of a drying system for raw materials used in Isan musical instrument production, utilizing waste heat from an air conditioning system. The case study was conducted at Ban Tha Ruea, Na Wa District, Nakhon Phanom Province. The system employed R-32 refrigerant in a vapor-compression refrigeration system with a cooling capacity of 36,000 BTU/h. The drying unit consisted of a shell-and-tube heat exchanger and an air-cooled heat rejection unit. Experiments were conducted using water flow rates of 15, 20, and 25 L/min, and an air flow rate of 1.10 kg/s to evaluate the drying system performance. In the experiments, 10 kg of wood for Isan musical instrument production was dried to a final weight of 4.45 kg, corresponding to a moisture content reduction of 15% on a dry basis. The system operation was controlled based on dry-bulb temperature. The results indicated that the water-cooled system, at a flow rate of 15 L/min, required 76 hours for drying, with an average drying chamber temperature of 40.70°C. In comparison, the air-cooled system required 49 hours, with an average temperature of 48.20°C. The coefficient of performance (COP) of the water-cooled system was 2.33 at a flow rate of 15 L/min, while the air-cooled system showed a COP of 2.16. The compressor power consumption of the water-cooled system was 2.99 kW, whereas that of the air-cooled system was 3.43 kW.