Enhancing ultra low temperature district heating systems with neighborhood-scale heat pump and triple-pipe distribution: A techno-economic analysis

Abstract

Ultra-Low Temperature District Heating (ULTDH) systems are advanced District Heating (DH) systems enabling the efficient utilization of low-temperature heat sources for heating systems. A significant challenge in ULTDH systems is the economic inefficiency associated with use of booster Heat Pump (HP) in buildings to achieve the desired Domestic Hot Water (DHW) temperature. To address this issue, this study proposes an innovative ULTDH system incorporating neighborhood-scale water-source booster HPs and distribution triple-pipes. Triple pipe's dual supply line capabilities facilitate the neighborhood-scale water-source booster HPs to be brought out at the neighborhood scale, demonstrating an intelligent approach. This approach reduces the capital investment and enhances the Coefficient of Performance (COP) by utilizing supply line of DH system as the heat source. A comprehensive case study is conducted to demonstrate the superior techno-economic performance of the proposed ULTDH system compared to Low Temperature District Heating (LTDH) as the benchmark solution. All components of both systems are sized by determining the DHW and Space Heating (SH) demands for each neighborhood. Thermodynamic analysis is conducted at a 1-min time resolution for an entire year. Six different heat production scenarios are developed to determine the Levelized Cost of Heat (LCOH). The results indicate that while the energy performance of the ULTDH surpasses LTDH, the rise in electricity prices favors the ULTDH system.