Professor Eduardo Cabrera Heat Exchanger Group 2: Karel Candelaria Marrero # 55478 Felix R Diaz Medero #75659 Ricardo Echegaray Romero # 75383 Alfredo Ortiz # 53273 Alex Rivera Betancourt # 10748 Professor Eduardo Cabrera

Outline Introduction Objective Theory Types of Heat Exchanger Study of components & importance Experimental Procedure

Introduction A heat exchanger is a device used to transfer heat between two fluids. This device avoid fluids mixing; it enters and exit with different temperature. Those temperatures depends on the kind of application and configuration given; can remove or add the heat from one fluid to the other fluid. This is a widely common process used in; space heating, refrigeration, air conditioning, power stations, chemical plants, petrochemical plants, petroleum refineries, natural-gas processing, and sewage treatment.

Objective Understand the principles of heat transfer between two fluid streams separated by a solid wall and how geometry affects its performance. The interpretation of the heat transfer in several types; (Shell & tube, Concentric tube and plate)

Theory/ Method of Analysis According to the flow operation, heat exchangers can be classified as: Parallel or Co-current flow - the two fluids enter the exchanger at the same end, and travel in parallel to one another to the other end. Hence, in a co-current design, the temperature of the cold stream outlet, Tc,out is always lesser than that of the hot stream outlet, Th,out. Therefore, the heat transfer is restricted by the cold stream's outlet temperature, Tc,out. Hot and Cold Fluids Direction Fluid temperature Variation

Theory/ Method of Analysis Countercurrent flow- In the countercurrent flow exchanger the two fluids flow are parallel to each other but in opposite directions. This type of flow arrangement allows the largest change in temperature of both fluids and is therefore most efficient. Hot and Cold fluids Direction. Fluid Temperature Variation

Theory/ Method of Analysis Cross flow- The fluids travels roughly perpendicular to another through the exchanger. A traditional cross-flow heat exchanger has a square cross-section and as a thermal efficiency of 40–65%. This flow operation is typically less expensive than other types of heat exchanger; it’s does not exchange humidity. Used in a cooling and ventilation system that requires heat to be transferred from one airstream to another. Hot fluid and Cold Fluid Direction

Theory Analysis Method/ Formula Log Mean Temperature Difference, LMTD Energy Balance Temperature Efficiency Overall heat exchanger coefficient Heat Losses Heat transfer Area Efficiency of the Heat Transfer Total Heat transfer

Theory/ Types of Heat Exchanger: Shell & Tube In order to transfer heat efficiently, a shell and tube heat exchanger should be use a large heat transfer area so its need as many tubes necessary mounted inside a cylindrical shell. On Shell and tube, there are two fluids can exchange heat; one fluid goes through the tubes and the other flows outside the tubes but inside the shell. The fluids; either liquids or gases, can be single or two phase and can flow in a parallel or a cross/counter flow arrangement. Figure 3.1 A shell and tube heat exchanger is a no mixing fluid heat exchangers.

Types of Heat Exchanger: Concentric Tube The tubular heat exchanger consist of two concentric tubes carrying the hot and cold fluids. The inner tube is used for the hot fluid and the outer annulus for the cold fluid. The primary advantage is the simplicity of their design, they can withstand high pressure operations. Also produce turbulent conditions at low flow rates, increasing the heat transfer coefficient, and hence the rate of heat transfer.

A Plate Heat Exchanger is a no Mixing Fluid Heat Exchangers Types of Heat Exchanger: Plate Heat In plate heat exchangers the fluids flow through grooves carved on plates. Many plates are attached together to form the channels by which the hot and cold fluid circulate. This heat exchanger is characterized by having a very large surface area to heat transfer. This plate type arrangement can be more efficient than the shell and tube. Advances in gasket technology have made the plate type increasingly practical. A Plate Heat Exchanger is a no Mixing Fluid Heat Exchangers

Study of the types of Heat Exchanger #1 Types of Heat Exchangers: Shell & Tube: Liquid to liquid heat transfers. Parallel or a cross/counter flow arrangement. Two fluids (either liquids or gases), of different starting temperatures. Concentric Tube: Two co-axial tubes carrying the hot and cold fluids. Their robust build means that they can withstand high pressure operations Plate: Single heating section configured for multi-pass operation #2 #3

Study of the types of Heat Exchanger The three types of heat exchangers has advantages and disadvantages according to the flow operation system differing it in the design and construction of a single or two phase type of operation. The effectiveness are largely determined by the direction of the flow within the exchanger. By theoretical analysis; the countercurrent flow heat exchanger design is the most efficient because allows the largest change in temperature of both fluid. The Shell and tube heat exchanger is the most common type of heat exchanger in industrial and petrochemical applications. It’s have the ability to transfer large amounts of heat in relatively low cost, serviceable designs. They can provide large amounts of effective tube surface while minimizing the requirements of floor space, liquid volume and weight.

Experimental Procedure: Overall efficiency To determine and compare the efficiency of the different heat exchanger configurations is necessary to measure the values of hot and cold temperatures in the inlet and outlet Differences between co-current and countercurrent operation To compare the differences between co-current and countercurrent operation is necessary to measure the different values of hot and cold temperatures in the inlet and outlet to calculate the rate of heat loss or gained to be compared. Overall heat transfer coefficient To determine the overall heat transfer coefficient the values of mass flow rate and temperature must be taken to calculate logarithm mean temperature difference and heat rate emitted.

Experimental Procedure: Effect of mass flow rate on heat exchanger performance To investigate the effect of the flowrate stream in the hot or cold fluid and the overall heat transfer efficiency. The values of the temperatures of the hot and cold sides must the measured in different combinations and compered with the countercurrent operation. Effect of driving gradient on heat exchanger performance To determine the effect on the driving gradient for the countercurrent flow operation the values of the temperatures (hot, cold) must be measured for the calculation the temperature efficient, overall heat coefficient.