年制冷压缩机行业深度调查及发展前景研究...美国 三、日本 第四节 全球制冷压缩机行业市场发展...国际贸易环境 第二节
年制冷压缩机行业... 　年厨房制冷设备市场发展现状调查及供需格局...深入的洞察力和预见力:我们不仅研究国内市场,对国际...重大展会提示等服务, 给您带来完善的一站式服务。 ... 　依托西班牙这个欧洲第一大空调市场,西班牙制冷展成为与意大利米兰制冷展、美国制冷展齐名的 同类国际顶级展事之一。西班牙是欧洲仅次于意大利的第二大组合式空调市场,...Heat Pumps | HVAC Heating and CoolingThis page uses JavaScript to progressively load the article content as a user scrolls.
Screen reader users, click the load entire article button to bypass dynamically loaded article content.
PasswordRemember meSign in via your institutionSign in via your institution
&RIS&(for EndNote, Reference Manager, ProCite)
&RefWorks Direct Export
& Citation Only
& Citation and Abstract
JavaScript is disabled on your browser.
Please enable JavaScript to use all the features on this page.
JavaScript is disabled on your browser.
Please enable JavaScript to use all the features on this page. This page uses JavaScript to progressively load the article content as a user scrolls. Click the View full text link to bypass dynamically loaded article content.
, 25 September 2013, Pages 398–404
Study on the operating performance of cross hot-gas bypass defrosting system for air-to-water screw heat pumps, , , , , , a School of Civil Engineering and Architecture, Zhejiang Sci-Tech University, Hangzhou 310018, Chinab Renewable Energy Research Group, Department of Building Services Engineering, The Hong Kong Polytechnic University, Hong Kong, Chinac Zhejiang Dun'an Artificial Environmental Equipment Co., Ltd., Zhuji 311835, China&Principle of cross hot-gas bypass defrosting method was introduced.&Thermal parameters' variation was experimentally studied.&No problem was found for continuous defrosting of the reverse-cycle defrosting.&Fluctuation of the pressure and temperature is less.Large-scale air-to-water screw heat pumps often operate with substantial frost formation on the air side of evaporators in winter, and the frost layer has to be melted away periodically. This paper presents a defrosting method for air-to-water screw heat pumps, i.e. the cross hot-gas bypass defrosting method, which uses two air heat exchangers for hot air from one air heat exchanger to melt the frost and absorb heat from another heat exchanger through the corresponding four-way reversing valve. The principle and process of this method are illustrated. The dynamic characteristics are experimentally investigated on a 359&kW air-to-water screw heat pump. The discharge temperature of the unit is at the normal range and the pressure varies little. A higher suction pressure is needed to achieve low pressure protection. The time period needed for the combination of heating and defrosting processes is short and it is not necessary to shutdown the compressor for defrosting so that a longer heating time period is possible. The inlet & outlet water temperature can be kept at around 30&&C and high heating COP is obtained. The test results show that the units work as expected.KeywordsCross hot-gas bypass defrosting; Air-to-water screw heat pump; Pressure; Temperature; COP
No articles found.
This article has not been cited.
No articles found.}