BACKGROUND Ground source heat pumps is a building energy conservation technique. The underground buried pipe heat exchanging system of a ground source heat pump (GSHP) is the basis for the normal operation of an entire heat pump system. METHODS Computational-fluid-dynamics (CFD) numerical simulation software, ANSYS-FLUENT17.0 have been performed the calculations under the working conditions o...

Nowadays, heat exchangers with twisted-tape inserts have widely been applied for enhancing the convective heat transfer in various industries such as thermal power plants, chemical processing plants, air conditioning equipment, refrigerators, petrochemical, biomedical and food processing plants. In general, twisted tape insert introduces swirl into the bulk flow which consequently disrupts a th...

An investigation on enhancement of heat transfer is carried out for a double pipe exchanger in which the outer wall inner provided with circumferential labyrinth passages. Rectangular and triangular cavities fixed tooth thickness, height, pitch are considered effect added structures characteristics discussed. A two-dimensional steady numerical simulation using ANSYS-FLUENT software. The flow Re...

fridges are used in various industries, and heat exchanger is one of the main components of these systems; therefore, efficiency analysis of these systems is very important. in many fridges, frost over the heat exchanger tubes or pipes affects the system operation and reduces heat transfer between the refrigerant and ambient, so defrosting systems are usually used to enhance heat transfer. desi...

In this study, in order to increase the heat transfer rate in concentric double-pipe heat exchangers by an active method, a rotating ball valve was mounted downstream of the outer pipe end and used as a pulse generator. In the experimental set-up, hot water (40-70 °C) was passed through the inner pipe with fixed mass flow rate (Reynolds number ≈ 10,200) while cold water was passed through the a...

One way to increase the heat transfer is to use perforated twisted tapes with different hole diameters, which largely improve heat transfer with an increase in the heat transfer area at the constant volume and more mixed flow. In the previous studies, the effect of nanofluids with perforated twisted tapes is less studied. In this work, the performance of water / iron oxide nanofluid in a double...

One way to increase the heat transfer is to use perforated twisted tapes with different hole diameters, which largely improve heat transfer with an increase in the heat transfer area at the constant volume and more mixed flow. In the previous studies, the effect of nanofluids with perforated twisted tapes is less studied. In this work, the performance of water / iron oxide nanofluid in a double...

in this paper, overall heat transfer coefficient and friction factor of water based γ-al2o3 nanofluid in a double tube counter flow heat exchanger have been measured experimentally under turbulent flow condition. for better dispersion of γ-al2o3 nanoparticles in distilled water, magnetic stirrer and ultrasonic vibrator (with a power of 240 kw and frequency of 35 khz) were implemented. the stabi...