Novel flue gas waste heat recovery system equipped with enthalpy wheel. (15th September 2019)

• Record Type: Journal Article
• Authors: Men, Yiyu; Liu, Xiaohua; Zhang, Tao; Xu, Xi; Jiang, Yi
• Is Part Of: Energy conversion and management. Volume 196(2019)
• Page Start: 649
• Page End: 663
• Publication Date: 2019-09-15
• Subjects: Flue gas -- Total heat recovery -- Enthalpy wheel -- Heat recovery efficiency -- Influencing factors; Direct energy conversion -- Periodicals; Energy storage -- Periodicals; Energy transfer -- Periodicals; Énergie -- Conversion directe -- Périodiques; Direct energy conversion; Periodicals; 621.3105
• DOI: 10.1016/j.enconman.2019.06.026
• Languages: English
• ISSNs: 0196-8904

Abstract

Highlights: Novel flue gas heat recovery system based total heat exchange is proposed. Dew point temperature of flue gas from the boiler increases to around 60 °C. Average boiler efficiency is 106% and average heat recovery efficiency is 88%. Wheel rotation speed and backwater temperature are important factors in operation. Abstract: Waste heat recovery from flue gas is an efficient way to increase the thermal efficiency of a gas-fired boiler. This paper proposes a novel flue gas waste heat recovery system, which comprises a condensing heat exchanger and an enthalpy wheel. The flue gas firstly flows through the condensing heat exchanger for heating boiler water, and then flows through the enthalpy wheel. The wheel, covered with desiccant material, acts as a medium for further heat and moisture transfer from the flue gas to the oxidizing air, resulting in an increase in the dew point temperature of the flue gas. Experimental results show that the average boiler efficiency reaches 106% and the average total recovery efficiency reaches 88%. The dew point temperature of the flue gas discharged from the boiler increases to around 60 °C, higher than that of conventional flue gas (around 55 °C). Consequently, more latent heat is recovered in the condensing heat exchanger by virtue of the proposed system. A mathematical model is established for further analysis based on the experimental results. The rotation speed of the enthalpy wheel and backwater temperature are key factors influencing the system performance.