helical coil heat exchangers are widely used in industrial applications ranging fromcryogenic processes, air-conditioning, and nuclear reactors to waste heat recovery due totheir compact size and high heat transfer coefficient. in this kind of heat exchangers, flowand heat transfer are complicated. this paper reports a numerical investigation of theinfluence of different parameters such as coil...

this study represents effect of four variables in performance of a heat-pump in two cities of tehran and rasht. a computer program has been developed, simulating a certain heat pump acting in different environments with different refrigerants in heating season. the analysis is based on a homogeneous model. effect of different refrigerants, depth of the buried heat exchangers and moisture conten...

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...

nanofluid is a new class of heat transfer fluids engineered by dispersing metallic or non-metallic nanoparticles with a typical size of less than 100 nm in the conventional heat transfer fluids.this article aims to investigate the overall and convection heat transfer coefficient and nusselt number of al2o3-water nanofluid flowing in a horizontal double pipe heat exchanger under turbulent flow (...

in this paper the numerical analysis of flow and time dependent heat transfer of micro-tube conveying nanofluid in laminar flow is investigated. in this study, convection heat transfer of nanofluid and base fluid and transient analysis for time-varying heat flux for time step of 0.0001 second are elucidated. it is observed that the pumping power of nanofluid flowing and the maximum temperature ...

elaboration of different toxins by enterotoxigenic e. coli has been considered as one of the main virulence factors contributing to the manifestation of disease caused by these microorganisms. various strategies have been employed to raise antibodies against these toxins as a line of defense. in this study, the 3’ terminus of the gene that codes for the binding subunit of the heat-labile entero...

in this paper by the introduction of the basic equipment of a solar cooling system, solar hydrogen ammonia refrigeration system as a solar cooling technique will be discussed. using heat collector and absorption refrigeration allows us to use residual heat, for cooling, heating and producing hot water and boiling water .this research focuses on methods of heat transfer from the sun into the gen...

Choosing between multiple ontological perspectives is crucial for reasoning about the physical world. Choosing the wrong perspective can make a reasoning task impossible. This paper introduces a Lagrangian plug flow ontology (PF) for reasoning about thermodynamic fluid flow. We show that this ontology captures continuously changing behaviors of flowing fluids not represented in currently implem...

heat exchangers are one of the most important devices of mechanical systems in modernsociety. most industrial processes involve the transfer of heat and more often they requirethe heat transfer process to be controlled. a heat exchanger is the heat exchanged betweentwo media, one being cold and the other being hot. there are different types of heatexchanger, but the type which is widely used in...

heat stress is a significant occupational health and safety for workers in petrochemical industries. heat stress is a combination of heat load individual and environmental factors impose on workers’ bodies, which in turn, have impacts on workers’ performance, safety, and health. the present paper is carried out to determine the heat stress levels in workplace and to compare it with allowed wet ...