This paper provides a review on the fouling mechanism and its effect onto the performance of finned tube heat exchangers in HVAC systems. Fouling tends to degrade the performance of heat exchangers by decreasing the heat transfer coefficient and increasing the air-side pressure drop across the heat exchangers. Air side fouling depends on a number of factors on the air side, including type and c...

This paper presents a comprehensive theoretical, experimental, and economic study on the application of nanofluids as heat transfer fluid in waste heat recovery systems. The research work was conducted in a steel-making complex in which a plate heat exchanger had been used to recover heat from hot process water. The system was theoretically modelled and the effects of using nanofluids as he...

Temperature of fluid stream through tube is a key variable in shell and tube heat exchanger. However, this variable is not easy to measure straightly. Therefore, a state observer is designed to estimate the tube temperature variable for direct control of shell and tube heat exchanger. A dynamical state space model is used to describe the heat exchanger process. Kalman filter based observer is d...

Abstract—Liquid spray heat exchanger is the critical equipment of temperature regulating system by gaseous nitrogen which realizes the environment temperature in the range of -180 °C~+180 °C. Liquid nitrogen is atomized into smaller liquid drops through liquid nitrogen sprayer and then contacts with gaseous nitrogen to be cooled. By adjusting the pressure of liquid nitrogen and gaseous nitrogen...

This paper assesses the approach introduced in a prior publication for the optimum design of condensers and evaporators aimed at balancing the heat transfer and pressure drop tradeoffs. Case studies carried out with different heat exchanger configurations for light commercial and household refrigeration applications are reported. The analysis indicated that a heat exchanger design with a high a...

This paper presents a Bond Graph (BG) modelling approach to add and exploit on existing Modelica models some information on the energy structure of the systems. The developed models in the ThermosysPro library (Modelica-based) are already validated against the experimental data in previous works. A plate heat exchanger (PHE), which is equipment for nuclear power plants, is considered as a case ...

The aim of this work is to bring forward a new style heat exchanger about hollow fiber membrane module, and to analyze the performance which can expectantly be applied in the lithium bromide absorption refrigeration system. Polyvinylidene fluoride hollow fiber membrane module was adopted as the new style solution heat exchanger, hot feed solution from the generator flowed into the lumen side of...

conceptual design of a waste heat recovery cycle is carried out in attempt to enhance the thermal efficiency of a steam power plant. in the recovery system, super-critical an co2 is employed as the working fluid operating in a brayton cycle. low grade heat rejected by the flue gases through the stack is used as the primary heat source, while a secondary heat exchanger utilizes the hot gases lea...

No portion of this publication may be altered in any form without prior written consent from the U.S. Department of Energy and the authoring national laboratory. both residential and commercial/institutional buildings. However, GHPs often have higher first costs than conventional systems making short-term economics unattractive. This disadvantage can be magnified in commercial buildings, many o...

INTRODUCTION Water quality is a frequently overlooked issue in the application of geothermal heat pump (GHP) systems. When considered at all, is often viewed as a problem unique to open loop systems. In residential open loop applications water is supplied directly to the heat pump’s refrigerant-to-water heat exchanger. If the water has a tendency to be scale forming, fouling of the heat exchang...