Cold-Climate 空气源热泵

The article below was originally published in summer 2018 by 家庭能源 Magazine. Article authors 本Schoenbauer, 亚历克斯Haynor and 妮可·凯斯勒, researched the performance of air source heat pumps in cold climates. 

Read more about our cold climate heat pump research

像空气源热泵(ASHPs)这样的高效技术在提高空间加热效率和降低寒冷气候下房屋的能源成本方面具有巨大的潜力. ASHP technology has been available for many years, 但直到最近, 在6和7气候带一年中最冷的几个月里，技术限制引起了人们对效率和可靠性的担忧. 最近几代的空气源热泵已经改进了一个逆变器驱动的压缩机和制冷剂的更新, making the systems better suited for cold-climate heating. 逆变器驱动的压缩机允许压缩机的速度调节，并在较冷的室外空气温度期间增加容量. 寒冷气候空气源热泵(ccASHPs)的效率和运行能力的提高为无法获得天然气供暖的家庭提供了节能空间供暖的机会, a market that is typically underserved.

冷气候空气源热泵可作为中央管道系统和无管道系统. Both system types are available with single and multizone indoor units. While the study described in this article focused on single-zone systems, multizone systems are expected to perform similarly.

中央管道系统的设计和安装是为了满足家庭的全部负荷，通过强制空气管道系统分配热量. 无管道系统通过没有管道系统的单个内部头将热量输送到家庭的特定区域. In cold-climate applications, 当室外冷空气温度限制了ccashp的热泵能力时，ccashp通常需要一个备用系统来提供热量, or prevent them from operating. 热泵与备用系统的集成是一个重要的设计和安装考虑因素, one that can drastically affect the performance of the system. Ducted systems typically use a propane furnace as a backup. 在室外空气温度下，当热泵的容量不再足够时，这些备份接管系统的负载. This temperature varies with the house load and the size of the system. It is usually about 10°F. 首页s with ductless systems typically do not have central ductwork. These homes often rely on electric-resistance baseboards for backup heating.

能源与环境中心(CEE)对新兴技术进行实地研究，这些技术有可能减少明尼苏达州的能源使用. 空气源热泵特别令人感兴趣，因为它们可以显著提高足球外围app哪个靠谱. 有必要进行实地研究，以评估这项新技术，并了解围绕ccASHP设计的供暖系统在实际安装中如何运行. In 2015, CEE conducted such a field study, 在CARD的资助以及大河能源和电力研究所的额外支持下.

CEE developed a field test methodology to characterize the ccASHP, and to assess its potential use in conservation improvement programs. The study was conducted beginning in 2015 as follows. 第一个, 明尼苏达州的特征数据被用来确定最能代表明尼苏达州ccashp市场的地点. Once the sites were identified, equipment was selected from a range of manufacturers and 安装 types, the purpose being to consider the full range of available technology. 然后在ccASHP系统中安装了详细的监控设备，以表征系统在现实世界中的性能. 最后, data were collected and analyzed to characterize equipment performance, and its performance was compared to the performance of baseline systems. The data analyzed included energy consumption, 运营成本, impact of the cold climate on system performance, 驾驶舒适性, 以及在明尼苏达州温度范围内系统效率的表征.

Cold-climate air source heat pumps operate in three ways. 图1 shows the operation of the ducted ccASHP in one of the monitored sites. 该图显示了性能系数(COP)或输送到家庭的能量与电力或丙烷消耗的能量的比率. The three modes of operation are heat pump heating (ashp.高温凝胶.On)，备用加热(lp.高温凝胶.开启)，融霜模式.

仅使用热泵的加热事件通常具有最高的cop，约为1.3 at the lower temperature change point (10°F) and increasing to about 3.5 in the shoulder heating seasons (around 50°F to 60°F). While the outdoor air temperature has the largest impact on the COP, 如图所示, heating cycles at the same outside air temperature did have a range of COPs. 循环COP的次要因素包括室内外机组组件的运行速率.

The second type of heating operation was the backup furnace mode. 这些事件发生在室外温度低于ccASHP预期满足家庭全负荷的温度点(这些系统的尺寸为10°F)。.

The final mode of operation was defrost. When the ccASHP is operational and outdoor conditions are below freezing, there is a risk that frost can form on the outdoor coil. 为了防止这种情况, ccASHP系统在除霜模式下运行，通过反转系统并将少量室内热量传回室外. There is a lot of variation in the defrost performance, because defrost can turn on mid-heating cycle. There are also times in an event when only the defrost is running, and almost no heat is provided to the home. This results in a COP near 0, because almost all of the heat goes to the outdoor unit to keep it from frosting. Some events have higher COPs because the heat pump has been on for a long time, and is only active for a small fraction of the event run time.

The high-resolution data were compiled to determine annual system performance. 这项研究的结果表明，居民和公用事业公司有机会将场地总能耗降低35%至50%.

These savings may be attributed to climate, ccASHP类型, and the system the heat pump replaced, 但在所有情况下, ccASHPs saved homeowners and renters significant amounts of energy and money. 图2显示了从基线供暖系统切换到ccASHP所实现的现场能耗减少. 在每个站点收集详细的数据，以便开发系统性能曲线. 性能数据允许估算跨一系列基线供暖系统和安装位置的ccASHP节约. Table 1 summarizes those results.

每个站点ccASHP和基线供暖系统的丙烷和电力使用

整体, CEE的研究发现，ccashp在系统容量和效率(COP或供暖季节性能因子)方面都达到了额定规格。. 适当的尺寸, 安装, and integration with backup heating systems, ccASHPs are an attractive replacement for homes with propane or electric heating.

明尼苏达州的许多电力公司和合作社都有现有的空气源热泵回扣计划，这些计划可以修改为包括使用ccashp供暖的好处. 本项目建议这些方案考虑安装要求，以确保满足所需的加热性能. One method would be to provide a tiered rebate structure. 例如, a low rebate could be provided for ccASHP systems installed only for cooling, 为冷却和季间供暖设计的系统提供中等水平的回扣, 对于设计用于冬季制冷和供暖的系统，回扣也很高.

Read the original article from 家庭能源 Magazine

Read more about our cold climate heat pump research