Techno-economic feasibility study of using heat pipe heat exchanger to improve dehumidification in air-handling unit

In this article, application of heat pipe to improve dehumidification in air-handling units (AHU) used in hot and humid climate conditions of north of Iran is studied. Coupled calculations of direct expansion (DX) coil and wrap around heat pipe (WAHP) heat exchanger are presented. Two types of buildings, i.e. with 100% and 25% fresh air are considered. Performance of AHU equipped with WAHP is compared with that of conventional AHU. The calculation results are compared and validated with outputs of an online software of a reputable WAHP manufacturer. For economic analyses, two scenarios are considered; first, WAHP is installed as a part of a brand new AHU in the factory or, second, WAHP is installed as a retrofit on an existing and operating AHU. Results show that 5% and 25% of electricity savings are obtained by using WAHP on AHU of buildings with 100% and 25% fresh air, respectively. Also, apart from the energy saving issue, the brand new AHU equipped with WAHP is more than 20% cheaper than the conventional AHU. For energy tariffs, two perspectives are considered: the consumer perspective (including significant subsidies) and the governmental perspective (including no subsidy). From a governmental perspective, adding a WAHP to the existing and operating AHU is profitable. For example, in a scenario, an IRR of 45% and a 5 years investment return was obtained.