In air-cooling applications with frost production, heat exchanger performance is often air-side limited, because the two-phase flow of the refrigerant provides excellent heat transfer coefficients, and because designers typically use a large air-side fin spacing for frost tolerance. The large fin spacing prolongs operation of the heat exchanger by mitigating the effect of the accumulating frost...

This paper proposes a trajectory planning and tracking approach for cylindrical heat exchanger process that is considered, under some assumptions, as a bilinear system. The proposed technique is based on orthogonal functions and especially the use of operational integration and product matrices. These operational tools allow the conversion of a bilinear differential state equation into an algeb...

This paper presents simulations of the integral coefficients of performance of a heat pump system coupled with a vertical ground heat exchanger (GHE). The GHE is simulated using different assumptions concerning the heat transfer in the ground, heat exchange between the ground and the brine and vertical variation of the brine temperature. The differences in the predicted performance coefficients...

The paper presents a fuzzy control based on parallel distributed fuzzy controllers for a heat exchanger. Each subcontroller is LQR designed and provides local optimal solutions. First, a Takagi-Sugeno fuzzy model is employed to represent a system. The stability of the system with the proposed fuzzy controllers is discussed. The simulation results are compared with classical PID control and illu...

In this study, a coil heat exchanger with an ice storage system is analyzed by theoretical analysis, numerical analysis, and experimental analysis. The dynamic characteristics of ice thickness variation is studied by means of unstable heat conduction theory in cylindrical coordinates, and the change rule of the ice layer thickness is obtained. The computational fluid dynamics method is employed...

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 (...

The Heat Pump with geothermal exchanger is one of the best methods to heat a building. The heat exchanger is an element with probabilities of failure due its size and due it is outside construction. The present study shows a novel intelligent system design to detect faults on this type of heating equipment. The novel approach has been successfully empirically tested under a real dataset obtaine...