Experimental investigation on a dehumidification unit with heat recovery using desiccant coated heat exchanger in waste to energy system

Abstract

Nowadays, waste-to-energy systems have attracted more and more attentions. Gasification technology is one of the most important methods of waste-to-energy utilization. For further using the residual heat of the gasification system, a desiccant dehumidification unit with heat recovery using desiccant coated heat exchanger (DCHE) driven by waste heat is developed. Two DCHEs are employed to remove moisture from fresh air. The hot water used in the regeneration process comes from the gasification combined heat and power (CHP) subsystem. Under the typical outdoor condition in Singapore (32 °C, 65% RH), the moisture removal of the system reaches 9.32 g/kgDA, the thermal COP is 0.70, and the waste heat utilization ratio approaches 74.2%. To improve the energy efficiency further, a heat recovery subsystem is adopted to recover the waste heat from the exhausted regeneration air. The recommended pre-regeneration time is 3 min, and the moisture removal is 9.01 g/kg DA, while the thermal COP and waste heat utilization ratio are remarkably increased to 1.34% and 86.5%, respectively. Detailed parametric analyses were carried out, including the influences of the cooling water flow rate, hot water flow rate and hot water temperature. This system combines desiccant coated heat exchangers and the gasification CHP subsystem innovatively to improve the energy utilization of waste-to-energy gasification system, which turns out an effective choice to achieve dehumidification and recover waste heat deeply.