Development of Solar Assisted Heat Pump Water Heating Systems

环境影响和标准能源的可得性变得越来越重要。人们还认识到，虽然发展新能源是必要的，但有意识地努力节约和更明智地使用能源也是必要的。长期以来，建筑一直被认为是能源效率的主要焦点，最雄心勃勃的努力旨在实现净零能耗目标。新的更高效的水加热策略对于实现这一目标至关重要，因为水加热是加拿大住宅的第二大能源消耗，约占总能源消耗的18%（每户19吉焦能源）。太阳能家用热水（SDHW）系统已被证明是一种经济有效且可靠的水加热方法，可减少住宅建筑的一次能源消耗。然而，在北方气候条件下，SDHW系统需要一个备用热源，以便在太阳能输入不足期间提供额外的热能。人们可以使用电阻加热器来提供这种备用加热，其中热输入与电输入的比例是1:1。另外，人们可以使用热泵，其中热量输入与电输入的比例可以在3:1或10:1的范围内，这取决于操作条件。从热力学的角度来看，使用这些电来运行热泵是一种更有效的能源利用。热泵和SDHW技术的协同组合为家庭用途提供热水或空气被称为太阳能辅助热泵（SAHP）。除了更好地利用电力之外，热泵还可以对进入太阳能吸收器的流体进行预冷却。较低的流体供应温度将减少吸收器的热损失，从而提高系统效率并增加系统在较冷天气下的运行时间。更重要的是，如果SAHP能够在不需要热泵时恢复到标准的SDHW系统，那么该系统就有可能满足节能建筑全年的需求。消除对备用热源的需求将有减少系统资本成本的额外好处。然而，要达到这一点，这些系统需要进一步发展。特别是，为了使SAHP发挥最大潜力，需要评估组件的尺寸和可靠性、智能控制策略以及系统与建筑物和居住者需求的交互。拟议的研究将解决当前SAHP技术的一些关键限制。总体目标是开发强大、可靠和经济上可行的SAHP系统，开发设计工具，使建筑商和房主能够对该技术做出明智的选择，并在太阳能和建筑科学相关领域培训HQP。最终，这将有助于减少建筑的能源需求，从而使加拿大受益。在未来五年中，拟议的计划将解决几个短期目标。首先，几个新的仅太阳能的SAHP系统配置将进行分析和实验研究，从而得到系统的精确模型。这些模型将用于开发创新的控制策略，使SAHP能够以最高效率运行。接下来，将评估这些系统与其他新型能源效率技术的兼容性，例如热回收和光电/太阳能热混合技术。最后，系统将被构建和操作，以评估系统在现实世界中的稳健性。与任何建筑技术一样，高效运行的关键是在其位置和使用特征的背景下理解和开发系统。

The environmental impact and availability of standard energy sources has become increasingly important. It is also recognized that while the development of new energy sources is necessary, so too is a conscious effort towards conservation and smarter use of energy. Buildings have long been considered a primary focus for energy efficiency, with the most ambitious efforts aimed at net-zero energy targets. New and more efficient water heating strategies are critical to meeting this goal, as water heating is the second largest energy consumer in Canadian residences at approximately 18% of total energy consumption (19 GJ of energy per household).Solar Domestic Water Heating (SDHW) systems have proven to be a cost effective and reliable method of water heating that reduces primary energy consumption in residential buildings. In northern climates, however, SDHW systems require a back-up heat source to provide additional thermal energy during period of insufficient solar input. One could use an electrical resistance heater to provide this back-up heating, where the ratio of heat input to electrical input is 1:1. Alternatively, one could use a heat pump, where the ratio of heat input to electrical input could be in the range of 3:1 or 10:1, depending on the operating conditions. From a thermodynamic perspective, using this electricity to run a heat pump is a far more efficient use of energy.The synergistic combination of heat pump and SDHW technologies to provide hot water or air for domestic purposes is called a Solar Assisted Heat Pump (SAHP). In addition to being a better use of electricity, the inclusion of a heat pump will pre-cool the fluid going to the solar absorber. Colder fluid supply temperatures will reduce thermal losses from the absorber, thereby improving system efficiency and increasing system run-time in colder weather. More importantly, if the SAHP is capable of reverting to a standard SDHW system when the heat pump is not needed, there is potential that the system could meet the year round demands of an energy efficient building. Removing the need for back-up heat sources would have the added benefit of reducing the capital cost of the system. To get to that point, however, the systems need further development. In particular, component sizing and reliability, smart control strategies, and system interaction with building and occupant requirements need to be assessed in order for the SAHP to reach its maximum potential.The proposed research will address some critical limitations of current SAHP technologies. The overarching goal is to develop robust, reliable, and economically viable SAHP systems, to develop design tools that will allow builders and homeowners to make informed choices about the technology, and to train HQP in fields related to solar energy and building sciences. Ultimately, this will benefit Canada by helping reduce the energy demands of buildings. Over the course of the next five years, the proposed program will address several shorter term objectives. Initially, several novel solar-only SAHP system configurations will be investigated both analytically and experimentally, resulting in accurate models of the systems. These models will be used to develop innovative control strategies which will allow the SAHP to operate at peak efficiency. Next, the compatibility of the systems with other novel energy efficient technologies, such as heat recovery and photovoltaic/solar thermal hybrids, will be assessed. Finally, the systems will be built and operated to assess system robustness in a real world setting. As with any building technology, the key to efficient operation is to understand and develop the system in the context of its location and usage characteristics.