Heat exchangers are the most important equipment in refrigeration processes. Design and modeling of heat exchangers operating at low temperatures are different from other regular heat exchangers. This study includes two sections. In the first section, design and modeling considerations needed for evaluating the real thermal behavior of heat exchangers at low temperatures were discussed. The...

An analytical model for a condenser with a wetted surface is developed by applying the governing conservations and rate equations and invoking the heat and mass transfer analogy. The heat exchanger is discretized in both the airflow and refrigerant-flow directions for a cross-flow configuration. Axial conduction along the tube walls is neglected and uniform distribution of water is assumed at t...

Results of a steady-state analysis performed for a class of distributed parameter systems described by hyperbolic partial differential equations defined on a one-dimensional spatial domain are presented. For the case of the system with two state variables and two boundary inputs, the analytical expressions for the steady-state distribution of the state variables are derived, both in the exponen...

This paper analyzes the performance of different controllers such as feedback, feedback plus feed-forward and internal model controller to regulate the temperature of outlet fluid of a shell and tube heat exchanger to a certain reference value. The transient performance and the error criteria of the controllers are analyzed and the best controller is found out. From the simulation results, it i...

If an air flow is injected into a liquid fluid, many ambulant air bubbles are formed inside the fluid. Air bubbles move inside the liquid fluid because of the buoyancy force, and the mobility of these air bubbles makes sizable commixture and turbulence inside the fluid. This mechanism was employed to enhance the heat transfer rate of a horizontal double pipe heat exchanger in this paper. Howeve...

We develop a trust region filter strategy for simultaneous optimal design of heat exchanger networks that includes detailed shell-and-tube exchangers. The first solves mixed-integer nonlinear programming (MINLP) formulation with shortcut models to generate candidate network topologies, which are then used in non-isothermal mixing (NLP) suboptimization embedded using modified (TRF) algorithm. An...

Now, environmental issues are the mostly discussed issue and become a top priority in world. Whether it's damage or pollution. The of pollution to environment ecology region, which have an impact on living organisms, both humans, animals plants. Environmental can occur land, water, air. With various forms pollution, methods handling different. This research will focus waters as well prevention,...

This current work mainly focuses on the enhancement of heat transfer and fluid flow characteristics shell-and-tube exchangers by incorporating dimples smooth or conventional tubes. With aid ANSYS (Fluent) commercial software package, Computational Fluid Dynamics (CFD) simulations under a steady-state condition were conducted exchanger having single shell 12 tubes (with without dimples), 50% baf...