Design and optimization of a CO2 heat pump system for a low-rise multi-unit residential building

建筑占加拿大二次能源使用的28%，是温室气体的一大来源。大约80%的住宅用途是用于空间供暖、制冷和热水需求。此外，加拿大住宅市场最近的房地产开发（作为一种减少碳足迹的策略，同时利用现有的基础设施）正在建设的多单元住宅建筑（murb）数量显著增加。目前，每个单元使用三个独立的系统来满足建筑负荷，而使用一个集成系统来满足所有单元的建筑负荷可以提高效率并降低资本成本。Ecologix提出开发一种新型热泵利用跨临界二氧化碳作为制冷剂。需要将二氧化碳提升到跨临界区域，以实现在所需的60℃下加热DHW的能力。本项目探讨二氧化碳热泵控制系统的潜力和发展，以满足城市综合管理中心的空间供暖、空间制冷和生活热水负荷。该项目将首先在稳态条件下对CO2热泵进行实验评估，以开发包括其传热特性在内的基线性能图。利用这些数据，TRNSYS将建立一个模型，并根据实验数据进行校准，并将其整合到加拿大一个典型的MURB的现有模型中。利用该模型进行参数化研究，以确定综合能源系统的最优配置和控制策略。

Buildings account for 28% of secondary energy use in Canada and represent a large source of greenhouse gases. Approximately 80% of residential use is attributed to space heating and cooling and hot water demands. Additionally, the Canadian residential market has seen an increase in intensification in recent real estate developments (as a strategy to reduce carbon footprint while taking advantage of existing infrastructure) with a significant increase in the number of multi-unit residential buildings (MURBs) being constructed. Currently, the building loads are being met in each unit using three independent systems, whereas improvements in efficiency and reduced capital costs would be possible with one integrated system meeting the building loads of all units. Ecologix has proposed developing a novel heat pump utilizing transcritical CO2 as the refrigerant. Elevating the CO2 to the transcritical region is required to achieve the ability to heat DHW at the required 60oC. This project examines the potential of, and the development of a control system for using a CO2 heat pump to meet the space heating, space cooling and domestic hot water loads of a MURB. This project will first experimentally evaluate the CO2 heat pump under steady-state conditions to develop a baseline performance map including its heat transfer characteristics. Using this data, a model in TRNSYS will be built and calibrated to the experimental data and integrated into existing models of a typical MURB in Canada. Using this model, a parametric study will be conducted to determine the optimal configuration and control strategy for the integrated energy system.