Arjstte 01 004

Advanced Research Journals of Science and Technology

ADVANCED RESEARCH JOURNALS OF SCIENCE AND TECHNOLOGY

(ARJST)

MINIMIZATION OF ENTROPY IN SHELL AND TUBE HEAT EXCHANGER

2349-9027

D.Chandramohan1, B.Mohan2, 1 Research Scholar, Department of Thermal Engineering, G.H Raisoni College of Engineering, Nagpur, Maharashtra, India.

2 Professor , Department of Thermal Engineering, G.H Raisoni College of Engineering, Nagpur, Maharashtra, India .

Abstract A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall to prevent mixing or they may be in direct contact. They are widely used in space heating, refrigeration, air conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, natural gas processing, and sewage treatment.

Entropy is a measure of the number of specific ways in which a system may be arranged, often taken to be a measure of disorder, or a measure of progressing towards thermodynamic equilibrium. The entropy of an isolated system never decreases, because isolated systems spontaneously evolve towards thermodynamic equilibrium, which is the state of maximum entropy.

This project presents the minimization of entropy production in heat exchanger using constrained thermodynamic optimization.

The aim of the project is to carry out design and optimization of counter flow shell and tube type heat exchanger by entropy minimization method.

In this project heat transfer coefficient and pressure drop on the shell side and tube side of a shell and tube heat exchanger have been obtained for mild steel, stainless steel, nickel tubes.

Design of shell and tube heat exchanger model is done and FEM based thermal analysis will be conducted to evaluate the thermal characteristics. *Corresponding Author: D.Chandramohan , Research Scholar, Department of Thermal Engineering, G.H Raisoni College of Engineering, Nagpur, Maharashtra, India.

Published: October 24, 2014 Review Type: peer reviewed Volume: I, Issue : II

Citation: D.Chandramohan,Research Scholar (2014) MINIMIZATION OF ENTROPY IN SHELL AND TUBE HEAT EXCHANGER

INTRODUCTION HEAT EXCHANGER: A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall to prevent mixing or they may be in direct contact.

Heat exchangers are devices used to transfer heat energy from one fluid to another. Typical heat exchangers experienced by us in our daily lives include condensers and evaporators used in air conditioning units and refrigerators. Boilers and condensers in thermal power plants are examples of large industrial heat exchangers. There are heat exchangers in our automobiles in the form of radiators and oil coolers. Heat exchangers are also abundant in chemical and process industries.

heat exchanger There is a wide variety of heat exchangers for diverse kinds of uses; hence the construction also would differ widely.

However, in spite of the variety, most heat exchangers can be classified into some common types based on some fundamental design concepts. We will consider only the more common types here for discussing some analysis and design methodologies.

A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall to prevent mixing or they may be in direct contact. They are widely used in space heating, refrigeration, air-conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, natural gas processing, and sewage treatment.

The classic example of a heat exchanger is found in an 11

Advanced Research Journals of Science and Technology

internal combustion engine in which a circulating fluid known as engine coolant flows through radiator coils and air flows past the coils, which cools the coolant and heats the incoming air.

A heat exchanger is a device designed to efficiently transfer or "exchange" heat from one matter to another. When a fluid is used to transfer heat, the fluid could be a liquid, such as water or oil, or could be moving air. The most well-known type of heat exchanger is a car radiator. In a radiator, a solution of water and ethylene glycol, also known as anti-freeze, transfers heat from the engine to the radiator and then from the radiator to the ambient air flowing through it. This process helps to keep a car's engine from overheating. Similarly, Lytron's heat exchangers are designed to remove excess heat from aircraft engines, optics, x-ray tubes, lasers, power supplies, military equipment, and many other types of equipment that require cooling beyond what air-cooled heat sinks can provide.

shell and tube heat exchanger Type of methods used in heat exchangers: Shell and tube The schematic diagram of a shell and tube heat exchanger. In shell and tube heat exchanger tube side oil and shell side water is used. In this diagram the red line indicates tube side flow and blue line indicate shell side flow.

In this diagram the redline of oil and green line of water indicate counter flow arrangement. In counter flow water enters at the bottom side and parallel flow water enters at top side. The heater is placed in the oil tank. The capillary thermostat is placed in the heater. The capillary thermostat is used to maintain the temperature of oil. The hot oil from the heat passed through the state point at this point inlet temperature of oil is measured. The oil enters into the valve 3 and enters into the tube of the shell & tube heat exchanger. The water from the tank is entering into the valve 1 to the state point. The inlet temperature of water at this point is measured. After this the water enters into shell side of the shell & tube heat exchanger.

The water is exit to the shell of the shell& tube heat exchanger. The water passed through the state point at outlet temperature of water is measured. The oil is entering into the tube and water is outside of the tube. The heat transfers take place. The cold oil from the shell & tube heat exchanger exit in to state point.

oil is measured.oil passes the valve 8 and goes to the oil reservoir.

Conduction: On a microscopic scale, heat conduction occurs as hot, rapidly moving or vibrating atoms and molecules interact with neighboring atoms and molecules, transferring some of their energy (heat) to these neighboring particles. In other words, heat is transferred by conduction when adjacent atoms vibrate against one another, or as electrons move from one atom to another. Conduction is the most significant means of heat transfer within a solid or between solid objects in thermal contact. Fluids especially gases are less conductive. Thermal contact conductance is the study of heat conduction between solid bodies in contact.

Steady state conduction (see Fourier's law) is a form of conduction that happens when the temperature difference driving the conduction is constant, so that after an equilibration time, the spatial distribution of temperatures in the conducting object does not change any further. In steady state conduction, the amount of heat entering a section is equal to amount of heat coming out.

Transient conduction (see Heat equation) occurs when the temperature within an object changes as a function of time. Analysis of transient systems is more complex and often calls for the application of approximation theories or numerical analysis by computer.

THERIOTICAL VALUES FOR ENTROPY Material

Entropy Generation rate(KW/k)

Mild steel

5.3264

Nickel

5.3437

Stainless steel

5.2990

Modified case (stainless steel)

4.475

Material thermal conductivity Vs Entropy generation rate

The outlet temperature is measured. The oil is enter into the valve 4and passed into oil reservoir. The water outside the shell and the oil inside the pipe. Heat transfer takes place between them. The exit temperature of cold

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Advanced Research Journals of Science and Technology

Modeling of shell & tube heat exchanger

Temperature:

 

Heat flux

Assembly of heat exchangers

DISCUSSION OF RESULTS

Thermal analysis of shell and tube heat exchanger

Material

Tube outlet Temperature

Heat Flux

Mild steel

60.576

0.36604

Stainless steel

59.102

0.5123

Nickel

60.595

0.9826

Modified tube using stainless steel

58.178

1.713

Material vs heat flux

the above image is showing imported model from pro-e to the format of (IGES) Initial Graphics Exchange Specification

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Advanced Research Journals of Science and Technology

CONCLUSION This project work deals with “MINIMIZATION OF ENTROPY PRODUCTION IN HEAT EXCHANGER” which is used in petro-chemical industry.

Initially data collection is done to understand the problem rectification methodology and consideration to calculate the entropy value. Theoretically entropy value is calculated for standard model and with the variation of materials nickel and stainless steel and also entropy value is calculated by changing the pipe parameter along with stainless steel.

A 3D model of heat exchanger parts and assemblies are prepared in creo parametric previously known as pro-engineer, analysis were conducted in finite element analysis using Anysis work bench software’s to conduct thermal analysis to find thermal behavior.

Thermal analysis is conducted on heat exchanger assembly by varying materials and pipe parameter as involved in theoretical calculations results are presented in tables and graphs formats for the easy understanding and comparison. As per the theoretical and analysis results as shown.

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AUTHOR D.Chandramohan, Research Scholar, Department of Thermal Engineering, G.H Raisoni College of Engineering, Nagpur, Maharashtra, India.

B.Mohan Professor , Department of Thermal Engineering, G.H Raisoni College of Engineering, Nagpur, Maharashtra, India .

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