Plate Heat Exchanger

"Heat exchangers are important, and used frequently in the processing, heat and power, air-conditioning and refrigeration, heat recovery, transportation and manufacturing industries. Such equipment is also important in electronics cooling and for environmental issues like thermal pollution, waste disposal and sustainable development. Various types of heat exchangers exist. In textbooks of heat transfer, commonly a brief chapter is provided for the introduction of heat exchangers and elementary theory of design, rating and sizing are presented. There also exist many books on heat exchangers either as textbooks or edited volumes. However, most such books treat a variety of heat exchanger types or specific problems and do not specialize in any particular heat exchanger type. Therefore, a lack of comprehensive and in-depth textbooks on specific heat exchangers exists. The present book concerns plate heat exchangers (PHEs), which are one of the most common types in practice. The overall objectives are to present comprehensive descriptions of such heat exchangers and their advantages and limitations, to provide in-depth thermal and hydraulic design theory for PHEs, and to present state-of-theart knowledge.

The book starts with a general introduction and historical background to PHEs, then discusses construction and operation (PHE types, plate pattern, etc.) and gives examples of PHEs in different application areas. Material issues (plates, gaskets, brazing materials) and manufacturing methods are also treated. The major part of the book concerns the basic design methods for both single-phase and two-phase flow cases, various flow arrangements, thermal-hydraulic performance in single-phase

flow and for PHEs operating as condensers and evaporators. Fouling problems are also discussed and in a section on extended design and operation issues, modern Research and Development (R & D) tools like computational fluid dynamics (CFD) methods are discussed. Unique features for PHEs are discussed throughout. Extensive R & D activities are carried out at companies and universities worldwide and originally this book was intended as an edited volume reflecting current research

and state-of the-art. However, as time elapsed and the lack of a comprehensive textbook was identified, the objectives were changed.

We believe this book will be useful as both a textbook at various educational levels and as a reference source book for PHEs.

We are grateful to the companies providing us with a lot of information on their products and their R & D works. We also appreciate the cooperation and patience provided by the staff at WIT Press and for their encouragement and assistance in producing this book."(1)2. IN LINE PLATE HEAT EXCHANGERS

" Bowman In Line Plate Heat Exchangers have been designed as a low cost alternative to our shell and tube types. They consist of numerous 316 stainless steel heat transfer plates, two outer covers and four connections copper vacuum-brazed together to form an integral unit.

Unlike other plate heat exchangers, they have a unique internal flow arrangement, which enables the inlet and outlet connections to be axially in line. This means that they can be installed directly in pipe work without any change of direction. Each fluid stream flows in series through alternate plates. As a consequence, the plate spacing is larger and internal velocities are higher than is normally the case with this type of heat exchanger, thus rendering them less prone to fouling.

These heat exchangers are suitable for heating, cooling, evaporating or condensing any fluids compatible with the materials of construction, the optimum unit for any duty can be computer selected by telephone in a matter of minutes.Mounting In Line Plate Heat Exchangers

The in line plate heat exchangers should be mounted as shown above. The direction and side through which any fluid flows does not matter, but they must be connected for counter flow. However, for condensing the arrangement shown in figure 2 must be used with the vapour entering at the top and the condensate leaving at the bottom and with the cooling fluid in counter flow."(2)

Gasketed Plate Heat Exchangers

Semi-Welded Plate Heat Exchangers

SIGMAWIG Welded Plate Heat Exchangers

Brazed Plate Heat Exchangers

Schmidt Brazed Plate Heat Exchangers

Brazed Plate Heat Exchangers represent the most compact, rugged and cost-effective means of transferring heat in many industrial and refrigerant applications. Built from 316 stainless steel with copper brazing materials, they provide exceptional corrosion resistance. The SB-Series features corrugated plates that produce highly turbulent flow in a true counter-current direction. This results in high efficiency and a very compact heat exchanger design. Due to the smaller size and reduced material content, they can be the most economical heat transfer choice.

Plates:316 Stainless Steel

Braze Material:CopperNickel

Connections:3/4" to 4" NPT, SolderingSAE Type, Flanged

Capacities:20 GPM to 385 GPM1/2 Ton to 100 Ton

Approvals:UL StampASME UM stamp is available by special order.

API Heat Transfer Brazed Plate Heat Exchangers are available for process and refrigeration applications. Made from stainless-steel plates and copper or nickel brazing materials, they are suitable for a wide variety of heat exchanger applications.

Brazed Plate models are available with dual circuits as shown here.

Typical applications include:

Refrigerant Evaporating & Condensing

Heat Pumps

Steam Heating

Engine or Hydraulic Oil Cooling

District or Zone Heating Systems

Swimming Pool Heating

Various Heating and Cooling Duties

Schmidt Gasketed Plate Heat Exchangers

SIGMA Plate Heat Exchangers utilize corrugated plates stacked between a fixed and a movable pressure plate. The corrugation patterns alternate for maximum operating pressures. As virtually all of the material is used for heat transfer, Plate Heat Exchangers can have large amounts of effective heat transfer surface in a small footprint. It is not uncommon that a Plate Heat Exchanger will have the same thermal capacity as a Shell & Tube five times larger.

The unique corrugation pattern pressed onto each Schmidt thermal plate produces the highest overall heat transfer rate by assuring highly turbulent flow and excellent fluid distribution across the entire surface. With high heat transfer rates and true counter current flow, Schmidt Plate Heat Exchangers economically handle close temperature approach requirements.

Operational Parameters

Temperature:Pressure:Capacity:Connections:-40F to 400FVacuum to 400 psig.5 to 8800 GPM1" to 14" - NPT, Studded, Flanged, Tri-clamp, others

Technical Data

Plates:StandardAISI 304 (1.4301)AISI 316 L (1.4404)AISI 316 Ti (1.4571)

SpecialAISI 904 LSMO 254Nickel AlloysTitaniam, Titanium PD

Thickness0.4 mm to 1.15 mm

Gaskets:StandardNitrile, EPDM, EPDM-HT, Chloroprene

SpecialH-NBR, NBR-HT, Viton, Butyle, PTFE coated (SIGMACOAT), gaskets approved for food applications

FixingMechanically (SIGMAFIX)Glued on

Frame:Painted Carbon SteelStainless Steel

Connections:StandardNitrile, EPDM, AISI 316 Tk

SpecialNickel alloys, Titanium, Titanium-PD

Codes:ASME, PED, ABS, LRS, GL, BV

SIGMAFIX Mechanical Gasket

API Heat Transfer's line of Schmidt Plate Heat Exchangers incorporate superior design features to ensure long term customer satisfaction.

Highest quality gaskets precisely fit the plate grooves for positive sealing and ease of maintenance.

Superior clip-on gasket design ensures proper fit during closing of the unit.

Double sealing design prevents the possibility of mixing the two process fluids. Leak detect feature ensures any leakage is to the atmosphere.

Zinc coated hardware provides long life.

All plate pack tightening is done from the fixed pressure plate to eliminate any stud interference.

All bolted construction for easier service.

Low volumetric fluid hold-up provides quicker response to heating and cooling demands, while reducing costs for more expensive process fluids.

Readily expanded for greater capacities, or totally new applications.

SIGMA Plate and Frame Exchangers are available in a variety of plate sizes for industrial, HVAC or sanitary applications.

Typical applications include:

Chemical

Pharmaceutical

Food & Beverage

Dairy

Petrochemical / Offshore HVAC

Marine

Oil Cooling

Breweries

Surface Trea

SEC Brazed Plate Heat Exchangers (BPHE)

The highly efficient design and excellent value of SEC Brazed Plate heat exchangers (BPHE) makes them a wise choice for your heat transfer applications. Manufactured to the highest standards utilizing the latest production technology our Copper, Nickel and Titanium, Single and Double Wall and Air Gap Brazed Plate Heat Exchangers meet the demanding quality requirements of the internationally recognized industry standards organizations.

SEC Brazed Plate heat exchangers are pressure rated for 435 psi at 437F. An economical version manufactured to the same high standards is rated at for 235 psi.

Applications:

Radiant Heating and Snow Melt

Domestic Hot Water Production

Solar and Geothermic Heating

Industrial Process Heat Recovery

Refrigeration - Condensers and Evaporators

Aquaculture and Marine Applications

Close Approach Heat Transfer

Beverage Production

Hydronic Heating

Oil Coolers

A specially designed corrugation pattern promotes highly turbulent flow characteristics. High turbulence dramatically improves the heat transfer rate and reduces the amount and the possibility of deposit build up.

SEC Brazed Plate Heat Exchanger Flow Channel Diagram

One-Pass means Channels are Parallel.Multi-Pass means a System of Channels is dividedinto groups which are connected in series.

SEC Brazed Plate Heat Exchangers (BPHE) offer the following Advantages..

Full Range of Models

Highly Efficient

Exceptional Value

Easy Instillation

OEM Inquiries Welcome

SEC Brazed Plate heat exchangers consist of specially formed stainless steel plates, vacuum brazed together to form a highly efficient heat transfer device. The plate size, number of plates and connection types are varied to match the customers heat transfer requirements precisely.

" A plate heat exchanger (Fig. 21) resembles a plate-and-frame filter press. It has both a fixed and movable end plate which are not heat transfer surfaces. Pressed between these end plates and corrugated or embossed plates having ports in the corners and gasketed, as shown in Fig. 22. the fluids flow in alternate spaces between the plates. The embossing patterns are so arranged that the plate are supported every few inches.

Plates are available in a wide variety of metals and alloys; gaskets are available in nitrile, butyl, silicone, fluorocarbon rubber, and in certain cases compressed asbestos. Exchangers have been made with 1500 (m2) (16,000 (ft2) of surface, with up to 700 plates, and with ports up to 40 cm (15.7 in). Plates range from 0.03 to 2.5 (m2) I0.3 to 26.9 (ft2)), 0.5 to 1.2 mm (0.02 to 0.05 in) thick, and 1.5 to 5 mm (0.06 to 0.5 in) in spacing. The operating pressure ranges from 0.1 to 1.5 MPa (14.5 to 217 lb(f)/(in2)). Temperatures are limited by the gaskets and for rubbers range from -25 to 150C (-13 to 300 F) and up to 260 C (500 F) for asbestos. Port velocities range up to 5 m/s (16.4 ft/s), with maximum flows of 2500 (m3)/h (1471 (ft3)/min.). The number of transfer units (NTU) ranges from 0.3 to 4 per pass, and optimum pressure drops are 30kPa/NTU (4.4 psi).

The advantages of plate exchangers are as follows: they have higher heat transfer rates and they produce less fouling than shell-and-tube exchangers, they are easy to clean and it is easy to change their plates if process are changed, they can handle slurries provided the particles are less than 0.5 mm (0.02 in), they require less space , and they are generally less expensive than shell-and-tube exchangers. The disadvantages are that the choice of fluids is limited by the chemical resistance and temperature limits the gaskets, that the large amount of gasketing leakage can be serious, that pressure is limited to 1.5MPa (217 psi), and that pressure drop in the ports limits flow rates.

The principal use of the plate exchanger is in liquid-liquid heat exchange. A wide range of viscosities are handled but the cooling of very viscous fluids can result in some maldistribution. Some condensation can be done, depending upon allowable pressure drops. In general, pressure drops in the ports makes gas-to-gas heat exchange undesirable.

Equations for approximating heat transfer and pressure drop [14] are:

For turbulent flow:

Nu = 0.25 Re^(0.65) Pr^(0.4)

For pressure drop:

h= 0.74Cp G Re^(-0.62) Pr ^(-2/3) (av/w)^( 0.14)

where Dh is the hydraulic equivalent diameter or approximately 2 times the clearances and Re(av) = DhG/.

For pressure drop:

P= 2fG(2)L/g(c) D(e)p

Where f= 2.5/Re^(0.3) An extensive discussion of design equations and methods is given in the second of a series of papers by Raju and Bansal [14].

Many different flow patterns are possible such as single-pass, multipass with equal passes, and multipass with unequal passes. If the flow volumes of the streams differ widely, then the unequal-pass arrangement is used. These various patterns also affect the LMTD corrections as shown in Fig. 25 to 31 in Part 1 of this chapter.

Distribution of fluid between the various plates is affected by the end connections. The U loop with all connections at the fixed head tends to give unequal flow distribution among the plates arranged for parallel flows. The Z connection (one set of connection charts on movable head) provides for more uniform distribution. The LMTD correction charts are based on an assumed uniform distribution.

The plate design, weather an intermated corrugated design or the chevron design, affects both heat transfer and pressure drop. The angle of the chevrons is also important. Intermediate results are obtained by mixing the plated, e.g., by using a combination of wide- and narrow-angle chevron plates.

Plate dimensions are dependent upon port size, which governs the plate width because of the flange dimensions on the nozzles, and the plate length, which is determined by the desired aspect ratio (heat transfer length to flow width), which has a lower limit of 1.8.

Plate designs vary from manufacturer and so will their performance.

All this information is proprietary; hence, available equations in the literature [12, 13, 14, 15] can only approximate the performance; therefore, one must go to the manufacturer to obtain a specific design.

Recommendation: If your process condition fall within the limitations of the plate exchanger then try to get access of the computer programs made available by the manufacturer. Most likely the plate exchanger will have less area and be less expensive that the shell-and-tube exchanger for the same duty."(6)Refrences :(1) L. Wang , B. Sundn & R.M. Mangli k, Plate Heat Exchangers(2) E.J. BOWMAN (Birmingham) LTD WEB SITE http://www.ejbowman.co.uk

(3) http://www.apiheattransfer.com(4) http://www.plateconcepts.com(5) http://www.brazedplate.com(6)W.M.Rohsenow, J.P.Hartnett , E.N.Ganic', Heat transfer applications,MC Grow Hill Book company