A theoretical study of the effects of different heating loads on the exergy performance of water-based and air-based space heating systems in buildings. (1st January 2022)

• Record Type: Journal Article
• Authors: Kazanci, Ongun B.; Shukuya, Masanori
• Is Part Of: Energy. Volume 238:Part C(2022)
• Publication Date: 2022-01-01
• Subjects: Exergy analysis -- Floor heating -- Radiators -- Air heating -- Auxiliary component -- Ground-source heat pump; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2021.122009
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: The present study investigated theoretically the exergy performance of floor heating, radiators, and air heating under three different space heating loads of 10, 30 and 50 W/m 2 . The effects of different supply and return water temperatures were studied for the radiators, and the effects of different supply air temperatures were studied for the air heating system. All systems were assumed to be connected to a boiler. The floor heating system was further analyzed assuming an air-to-water heat pump, and a ground-source heat pump. Floor heating was the optimal heating system due to its low exergy demand. The separation of thermal environmental conditioning and ventilation was an efficient solution. The results prove thermodynamically that renewables (i.e., ground source heat in the present study) and low temperature heating systems (i.e., floor heating in the present study) are a resource- and exergy-efficient combination proven by their exergy efficiencies up to 10.5%. The critical COP concept was validated (2.57 in this study). The power use of auxiliary components might seem negligible in terms of energy; however, it is critical in terms of exergy as it affects the exergy performance drastically. The relative importance of auxiliary power becomes more critical at low space heating loads. Highlights: Radiant floor heating was the optimal heating system. Separation of space thermal conditioning and ventilation was an exergy-efficient solution. Proved thermodynamically that renewables and radiant systems is an exergy-efficient match with exergy efficiency up to 10.5%. Developed and validated the critical COP concept, which was 2.57 in this study. Power use of auxiliary components is critical for the system exergy performance.