In residential buildings, domestic hot water (DHW) used for showering and handwashing produces significant amounts of hot drain water (DW), which is typically wasted. This study proposes a horizontal drain water heat recovery (DDWHR) unit to capture waste heat from DW and improve overall DHW system efficiency with the focus on thermal exchange in a compact installation suitable for high-rise apartment buildings. Experiments under different operating conditions were conducted to evaluate the DDWHR unit’s thermal performance and energy-saving potential. Results showed that the proposed DDWHR unit achieved energy efficiency of 90–95%, depending on operating conditions, due to high heat recovery rates. In the entire DHW system, the DDWHR unit demonstrated approximately 15% heating energy savings compared to conventional DHW setups. Also, nationwide adoption of the DDWHR unit in two-person apartments could reduce gas costs by about 14% annually. The findings of this study indicate that the horizontal DDWHR unit can effectively promote sustainable DHW use in high-rise residential buildings and offers a promising solution for improving energy efficiency in DHW systems.

中文翻译：

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探索高层公寓楼中水平生活排水热回收系统的能源效率和节约潜力


在住宅建筑中，用于淋浴和洗手的生活热水 （DHW） 会产生大量的热排水 （DW），这些水通常会被浪费掉。本研究提出了一种水平排水热回收 （DDWHR） 装置，以捕获 DW 中的废热并提高整体 DHW 系统效率，重点是在适用于高层公寓楼的紧凑安装中进行热交换。在不同运行条件下进行了实验，以评估 DDWHR 装置的热性能和节能潜力。结果表明，由于热回收率高，拟议的 DDWHR 装置实现了 90-95% 的能源效率，具体取决于运行条件。在整个 DHW 系统中，与传统的 DHW 装置相比，DDWHR 装置节省了约 15% 的加热能源。此外，在全国范围内在两人公寓中采用 DDWHR 装置每年可降低约 14% 的天然气成本。本研究的结果表明，卧式 DDWHR 装置可以有效促进高层住宅建筑中可持续地使用生活热水，并为提高生活热水系统的能源效率提供了有前途的解决方案。