Performance Analysis of Heat Pump Dryer with Unit-Room in Cold Climate Regions

Abstract

This study presents the development and evaluation of a novel partially open-loop heat pump dryer with a unit-room (HPDU). The unit-room was designed to enable the ambient air to be mixed with the return air, thereby reducing the influence of the ambient air on the system performance, while maintaining a high system thermal efficiency. A modelling system for the HPDU was developed and validated based on a real-scale experimental study. By using the modelling system, the system characteristics under different ambient conditions and bypass factors were analyzed. The energy benefit of the proposed HPDU was quantified through a comparative study with a closed-loop heat pump dryer (CHPD). It is evident that a maximal specific moisture extraction rate (SMER) and a minimal total energy consumption (TEC) existed when changing the bypass factor of the HPDU under certain ambient temperatures. Compared to the CHPD, the coefficient of performance (COP) of the HPDU increased by up to 39.56%, presenting a significant energy benefit for the application of HPDU.

Review on low‐temperature heat pump drying applications in food industry: Cooling with dehumidification drying method

“…When moisture-laden air passed through the evaporator, it becomes dehumidified cold air. The RH of this dehumidified air assumed to reach 100%, while the temperature of the condensate water assumed to be the temperature of the dehumidified cold air at the evaporator outlet (Yuan et al, 2019). Then remained air flows to the condenser where refrigerant condenses and removes heat.…”

Investigation of performance and drying kinetics of the closed, partially open, and open heat pump drying systems

“…This energy can be recovered using the HPD system (HPDS) (Taşeri et al, 2018). Yuan et al (2019), in their research, stated that HPDSs can be divided into three categories depending on air loops: Open-loop type (Liu et al, 2017;Singh, Sarkar, & Sahoo, 2019); partially open-loop type (Liu et al, 2018;Taşeri et al, 2018;TeGrotenhuis, Butterfield, Caldwell, Crook, & Winkleman, 2017); and closed-loop type (Aktaş et al, 2019;Pal & Khan, 2010;Rahman, Saidur, & Hawlader, 2013). In the open-loop HPDs (OHPDs), the drying performance is directly influenced by the ambient conditions (Achariyaviriya, Soponronnarit, & Terdyothin, 2000), because the heat source is typically the ambient air.…”

Influência da configuração de instalação dos trocadores de calor na operação de um secador assistido por bomba de calor

“…A configuração 2 foi a mais encontrada em trabalhos com secadores assistidos por bomba de calor (Strømmen et al, 2003;Teeboonma et al, 2003;Sarkar et al, 2006;Pal & Khan, 2010;Patel e Kar, 2012;Housain et al, 2013;Zigler et al, 2013, Closas & Villanueva, 2014Aktas et al, 2014;Minea, 2015;Yuan et al, 2019;Ponwapee et al, 2021). Housain et al…”

“…Notadamente, as bombas de calor são equipamentos muito eficientes quando se trata de aquecimento, isso pelo fato de não converterem a energia elétrica diretamente em calor e, sim, fazer uso desta para retirar calor de uma fonte a baixa temperatura e rejeitá-lo em um depósito a temperatura mais elevada. Com isso, as bombas de calor conseguem produzir de 3 a 7 vezes mais calor que uma resistência elétrica de mesma potência, o que implica dizer que uma bomba de calor pode substituir uma resistência elétrica consumindo de um terço a um sete avos da potência desta (Sarkar et al, 2006;Aktas et al;Yuan et al, 2019). Isto faz com que a bombas de calor de calor também sejam opções mais vantajosas frente a queima direta de óleo e gás para aquecimento (Jordan et al, 2016, Jordan et al, 2019.…”