An innovative hollow fibre-based dehumidification–cooling system for residential building retrofits: experiments and case study

Building retrofitting is an important method to reduce energy consumption; however, considering the post-retrofit building performance of traditional energy efficient interventions, the issue of indoor air quality, such as humidity and sanitation, is often complained about by occupants. Therefore, independent controls for humidity and temperature in air conditioning systems needs to be further improved using advanced technologies to improve comfort levels in order to increase the retrofit rate of residential buildings. This paper presents an innovative hollow fibre-based dehumidification-cooling system with pre-cooling solution for residential building retrofits, with the aim of realising an accurate humidity control with less energy consumption compared to commercial heat pump-based air conditioners. The proposed concept for a cooling and dehumidification system is a two-step process by applying hollow fibre system, which consists a liquid desiccant dehumidification cycle, and a water evaporative cooling cycle. The experiment results show that the maximum overall cooling and dehumidification COP reached 4.36 with outlet air temperature of 27.6°C and humidity of 70.7%, when the inlet air has a temperature of 40°C and humidity of 80%, under the condition of pre-cooling degree of 0.3. Besides, the maximum dehumidification COP, and cooling COP reaches 7.10 and 9.04 respectively, with pre-cooling degree of 0.5, under the NTU value of 4.5. Moreover, an Italian residential building used as a case study to investigate the energy saving performance with the dehumidification and cooling performance under the hot and humid summer in Mediterranean area from May to September. The simulation results illustrates that approximately 84% reduction of the cooling energy consumption achieved (from 5.99 kWh/m2 to 0.96 kWh/m2) and 63% of comfort hours increased (from 4301 hours to 7031 hours), which is under humidity control section between 40% and 60% and temperature control section between 20°C and 22°C, if compared with a traditional commercial split air conditioner.