How efficient are plate heat exchangers?
There are numerous advantages associated with plate heat exchangers:
- Plate heat exchangers weigh less, require less space and are more efficient compared to other heat exchanger designs of the same size.
- Replacing and cleaning of the plates is a simple task because the plate stack can be opened easily.
- And unlike shell and tube heat exchangers, plate heat exchangers do not require additional space for dismantling.
What does a plate heat exchanger do?
With a plate heat exchanger, heat easily crosses the surface which separates the hot fluid from the cold one. This allows you to heat or cool liquids or gases with minimal energy levels. The temperature difference constitutes the “driving energy” of the exchanger.
What type of heat exchanger is more efficient?
- When the amount of fluids are more we will use plate n frame heat exchanger .
- When required heat transfer cofficient is more then double pipe heat exchanger is efficient .
- When amount f fluids are huge and temperature difference required is more and pressures and temparatures are more we will go for shell and tube heat exchanger .
How are gasketed plate heat exchangers work?
How gasketed plate heat exchangers work. In a gasketed plate heat exchanger, the plates are fitted with elastomeric gaskets which seal the channels and direct the fluids into alternate channels. The plate pack is assembled between a frame plate and a pressure plate, and compressed by tightening bolts fitted between these plates.
What is the working principle of plate heat exchanger?
So the principle of plate heat exchanger working is – The fluids flowing through the flow channels on the plates flow through the gaskets without being mixed with each other and the desired heat transfer is carried out due to the temperature difference.
What are the advantages of the plate and frame heat exchangers?
Advantages of Plate Heat Exchangers; A lower cost option wherever stainless steel is required. Higher operating pressure capabilities. Higher temperature capabilities. Ideal for small district heating, beverage cooling, food and pharmaceutical production and low duty oil cooling applications.
What are the 3 types of heat exchangers?
Types of Heat ExchangersShell and tube heat exchangers.Double pipe heat exchangers.Plate heat exchangers.Condensers, evaporators, and boilers.
What does a plate type heat exchanger consist of?
A plate exchanger consists of a series of parallel plates that are placed one above the other so as to allow the formation of a series of channels for fluids to flow between them. The space between two adjacent plates forms the channel in which the fluid flows.
Where are plate and frame heat exchangers used?
Some of the applications where this high efficiency is evident when using the Graham Brazed or Gasketed Plate Heat Exchangers are:Water heaters.Cooling tower isolation.Free cooling.Waste heat recovery.Heat pump isolation.Thermal (ice) storage systems.
What are the disadvantages of plate heat exchangers?
DISADVANTAGES OF PLATE HEAT EXCHANGERSLeakage. Plate heat exchangers are designed to allow plates and gaskets to be inserted between them. ... Higher pressure drops. ... Not beneficial for large fluid temperatures. ... It doesn't work well with very high fluid temperatures.
What are the 4 types of heat exchanger?
4 Types of Heat Exchangers and ApplicationsDouble Tube Heat Exchangers: Double tube heat exchangers use what is known as a tube within a tube structure. ... Shell and Tube Heat Exchangers: ... Tube in Tube Heat Exchangers: ... Plate Heat Exchangers:
Why is plate heat exchanger better than shell tube?
Plate heat exchangers are up to five times more efficient than shell-and-tube designs with approach temperatures as close as 1°F. Heat recovery can be increased substantially by simply exchanging existing shell-and-tubes for compact heat exchangers.
What type of heat exchanger is most efficient?
Plate exchanger is the most efficient due to turbulent flow on both sides. High heat-transfer coefficient and high turbulence due to even flow distribution are important.
What is heat exchanger used for?
Heat exchangers are used to transfer heat from one medium to another. These media may be a gas, liquid, or a combination of both. The media may be separated by a solid wall to prevent mixing or may be in direct contact.
How long does a plate heat exchanger last?
In most cases, the heat exchanger determines how long your furnace will last. The heat exchanger is responsible for heating the air that circulates through your home in the winter. Heat exchangers usually last about 15 years. If you invest in maintenance, yours might even last 20.
How can you make a plate heat exchanger more efficient?
The method to increase the logarithm mean temperature difference of heat exchanger is to adopt counter current or near counter current mixed flow pattern as far as possible, increase the temperature of hot side fluid as far as possible, and reduce the temperature of cold side fluid.
How many heat exchangers are there?
There are three primary classifications of heat exchangers according to their flow arrangement. In parallel-flow heat exchangers, the two fluids enter the exchanger at the same end, and travel in parallel to one another to the other side.
What are types of heat transfer?
Heat can be transferred in three ways: by conduction, by convection, and by radiation.Conduction is the transfer of energy from one molecule to another by direct contact. ... Convection is the movement of heat by a fluid such as water or air. ... Radiation is the transfer of heat by electromagnetic waves.
What are the two most common type of heat exchanger used onboard?
Though there are many more types of heat exchangers that are used shore side, plate and shell and tube heat exchangers are the most common type of heat exchangers found aboard ocean-going vessels.
What type of heat exchanger is a radiator?
Most commonly made out of aluminum, automobile radiators utilize a cross-flow heat exchanger design. The two working fluids are generally air and coolant (50-50 mix of water and ethylene glycol). As the air flows through the radiator, the heat is transferred from the coolant to the air.
Are plate heat exchangers efficient?
The plate heat exchangers are one of the most efficient heat exchangers. The efficiency rate of the plate heat exchanger is approx—90%.
What are plate heat exchangers used for?
A plate heat exchanger is a well suitable exchanger to exchange heat between low pressure and medium pressure fluids. They are used in boilers, com...
Which heat exchanger is best?
Plate heat exchangers are most effective because of the turbulence on both sides. High turbulence and high heat transfer rate are important for eve...
Who invented the plate heat exchanger?
In 1923, Dr Richard Seligman was invented the plate heat exchanger.
How long does a plate heat exchanger last?
A heat exchanger can continuously work for up to 10 years.
What is plate heat exchanger?
A plate heat exchanger is a type of heat exchanger that uses metal plates to transfer heat between two fluids. This has a major advantage over a conventional heat exchanger in that the fluids are exposed to a much larger surface area because the fluids are spread out over the plates. This facilitates the transfer of heat, and greatly increases the speed of the temperature change. Plate heat exchangers are now common and very small brazed versions are used in the hot-water sections of millions of combination boilers. The high heat transfer efficiency for such a small physical size has increased the domestic hot water (DHW) flowrate of combination boilers. The small plate heat exchanger has made a great impact in domestic heating and hot-water. Larger commercial versions use gaskets between the plates, whereas smaller versions tend to be brazed.
How are heat exchanger plates spaced?
The plates are often spaced by rubber sealing gaskets which are cemented into a section around the edge of the plates. The plates are pressed to form troughs at right angles to the direction of flow of the liquid which runs through the channels in the heat exchanger.
Why is plate heat exchanger important?
The shape of plate heat exchanger is very important for industrial applications that are affected by pressure drop. Extending surfaces by finning and inserts are some types of ways for heat exchanger enhancements. On both the inner and outer, finning tubes may be finned.
What is the outer casing of a heat exchanger made of?
The walls of the pipe are usually made of metal, or another substance with a high thermal conductivity, to facilitate the interchange, whereas the outer casing of the larger chamber is made of a plastic or coated with thermal insulation, to discourage heat from escaping from the exchanger. The plate heat exchanger (PHE) was invented by Dr Richard ...
Why is the size of a plate heat exchanger smaller?
For the same amount of heat exchanged, the size of the plate heat exchanger is smaller, because of the large heat transfer area afforded by the plates (the large area through which heat can travel). Increase and reduction of the heat transfer area is simple in a plate heat-exchanger, through the addition or removal of plates from the stack.
How does a heat exchanger work?
The concept behind a heat exchanger is the use of pipes or other containment vessels to heat or cool one fluid by transferring heat between it and another fluid. In most cases, the exchanger consists of a coiled pipe containing one fluid that passes through a chamber containing another fluid. The walls of the pipe are usually made of metal, or another substance with a high thermal conductivity, to facilitate the interchange, whereas the outer casing of the larger chamber is made of a plastic or coated with thermal insulation, to discourage heat from escaping from the exchanger.
What is the most efficient method to flush out all the waste and dirt that over time decreases the efficiency of the heat?
Fouling capacity, reliability and safety are other considerations that should be tackled. First is Periodic Cleaning. Periodic cleaning (on-site cleaning) is the most efficient method to flush out all the waste and dirt that over time decreases the efficiency of the heat exchanger.
What is a Plate Heat Exchanger?
A plate heat exchanger uses a series of metal plates to move heat from one fluid to other. These plates are positioned over each other to create a channel’s series so that fluid can move between them. In the 1920s, Dr. Richard Seligman invented the plate heat exchanger (PHE).
Working of Plate Heat Exchanger
A plate heat exchanger is a type of heat exchanger that contains a series of metal plates to transmit heat between fluids. The plate heat exchanger works on the principle of thermodynamics. In these exchangers, each plate has a confined, hollow tubular shell.
Design of plate and frame heat exchanger
Plate heat exchangers (PHE) are specifically designed to transfer heat between low-pressure fluid and medium-pressure fluid. Brazed, semi-welded, and welded exchangers use to heat exchange between high-pressure fluids.
FAQ Section
The plate heat exchangers are one of the most efficient heat exchangers. The efficiency rate of the plate heat exchanger is approx—90%.
What is Plate Heat Exchanger?
A plate heat exchanger is used to transfer heat energy from one fluid to another. These fluids never encounter each other due to being separated by the heat exchanger. Typically, a plate heat exchanger will consist of several parallel plates positioned above each other, thus creating a passage in which the fluid can flow between. The spacing between two opposite plates provides a channel for the fluid to flow through.
How are plate heat exchangers constructed?
How is Plate Heat Exchanger Constructed? A plate exchanger consists of a series of parallel plates that are placed one above the other so as to allow the formation of a series of channels for fluids to flow between them. The space between two adjacent plates forms the channel in which the fluid flows.
What is Plate Heat Exchanger Working Principle?
The purpose of a plate heat exchanger is to transfer thermal energy between two fluids, without the fluids mixing together. For example, in building services, you might want to transfer heat from a primary loop connected to a boiler over to a separate secondary loop, maybe in a district heating network. In manufacturing, you may want to cool down some oil using water, but obviously you don’t want to mix the oil and the water together.
What are Different Types of Plate Heat Exchanger?
Brazed Plate Heat Exchangers: These are used largely for refrigeration & industrial applications. The main benefit of brazed plate heat exchangers is that they are highly resistant to corrosion. This is due to them being made from a combination of stainless steel and a copper brazing.
How are heat exchanger plates spaced?
The plates are often spaced by rubber sealing gaskets which are cemented into a section around the edge of the plates. The plates are pressed to form troughs at right angles to the direction of flow of the liquid which runs through the channels in the heat exchanger.
What is the benefit of a semi-welded plate heat exchanger?
The main benefit of a semi-welded plate heat exchanger is that high temperature, corrodible fluids can be transferred on one side while the other side allows for easy servicing.
What is a semi-welded heat exchanger?
Semi-Welded Plate Heat Exchangers: This variety of plate heat exchanger combines the use of welded and gasketed plates. The heat exchanger contains twin sets of plates which have been welded together. These have then been gasketed to other sets, thus making one of the fluid passages welded and another gasketed. The main benefit of a semi-welded plate heat exchanger is that high temperature, corrodible fluids can be transferred on one side while the other side allows for easy servicing.
What Is a Plate Heat Exchanger?
Plates exchanger consists of a series of parallels plates that are placed one on top of the other to allow the formation of a series of channels for fluid to flow between them. The space between two adjacents plates forms the channel in which the fluid flows.
What type of heat exchanger works well with a small temperature difference between the hot and cold fluid?
A flat plates heat exchanger works well with a small temperature difference between the hot fluid and the cold fluid.
Why do heat exchangers need insulation?
Heat exchangers must be adequately insulated to minimize heat loss. Since heat exchangers are routinely inspected and maintained, insulation is not practical at a stay. Normally, the heat exchanger experiences a touch temperature that is different from the ambient temperature, with valuable heat likely to be carried away.
Why are semi-welded heat exchangers used?
Semi-welded heat exchangers are perfects for transferring expensive materials because they have little risk of fluid loss. API Schmidt-Breton offers all four variants. Each type is suitable for many applications in different industrial sectors.
How many plates are in a singles exchanger?
The number of plates in a singles exchanger ranges from only ten to several hundred, so the surface exchange areas reach thousands of square meters. The figure shows the flow of fluid inside the exchanger. Fluids split into several parallel currents and can produce a complete countercurrent.
Why are corrugated plates used?
Typically, these plates are corrugated to increase turbulence, thermal exchange surface and to provide mechanical rigidity to the exchanger. Corrugation is obtained by cold forging of sheet metal with a thickness of 0.3 mm to 1 mm.
What causes a higher heat transfer coefficient?
Narrow passages for fluid flow, which lead to a higher overall heat transfer coefficient, also lead to a higher pressure drop, & thus a higher cost for pumping than shell and tube heat exchangers.
Why are plate heat exchangers so compact?
This is because of the combination of high-value heat transfer and the general compact configuration of the flat plates.
What is the purpose of a heat exchanger?
The main functionality of a heat exchanger is to transfer heat between two fluids at different temperatures. Most exchangers consist of a coiled pipe that allows one fluid to passes through a chamber which holds another fluid. The pipes’ walls are metal, or another substance containing a high thermal conductivity to enable the interchange of heat. The chamber in which the pipes are held are made out of plastic or coated with thermal insulation to keep heat from escaping.
What is a semi-welded heat exchanger?
Semi-Welded heat exchangers are great for transferring expensive materials due to their low risk of fluid loss.
Why are heat exchangers so leaky?
Leakage. Plate heat exchangers are designed to allow plates and gaskets to be inserted between them. This increases the potential for leakage as gaskets age. Especially when compared to shell and tube or spiral heat exchangers.
What are the disadvantages of plate heat exchangers?
Though there are some big advantages to plate heat exchangers, there are also some disadvantages when comparing them to other heat exchangers: 1 Leakage. Plate heat exchangers are designed to allow plates and gaskets to be inserted between them. This increases the potential for leakage as gaskets age. Especially when compared to shell and tube or spiral heat exchangers. 2 Higher pressure drops. Plate heat exchangers consist of narrow passageways for fluid to flow, which leads to a high heat transfer. This results in a higher pressure drop and a higher cost for pumping than shell and tube heat exchangers. 3 Not beneficial for large fluid temperatures. Flat plate heat exchangers don’t work as well as shell and tube exchangers in cases where there’s a large temperature difference between two fluids. 4 It doesn’t work well with very high fluid temperatures. The gaskets among plate heat exchangers can restrict temperature limitations.
How does heat transfer take place?
The heat transfer takes place as one fluid flows through the tubes while another fluid flows over the tubes in the shell. If you’re using a simple plate heat exchanger, the plates are intended for liquid-liquid exchange at low to medium pressures.
Why remove plates?
You can remove plates easily for cleaning, expansion, or replacing purposes, which helps reduce maintenance costs. Brazed plate heat exchangers – Used in many industrial and refrigeration applications, these exchangers can be very efficient and compact. This tends to make them a highly economic choice.
What factors influence what type of plate heat exchanger is best for a specific duty?
These can include type of media and refrigerant, design pressure, capacity needs, efficiency demands, serviceability requirements, and many more. Based on the specific needs and conditions of your operation, ...
Is Alfa Laval a reliable heat exchanger?
For 90 years, Alfa Laval has been developing plate heat exchanger technology tailored to our customers’ applications. Today we offer the market’s most comprehensive portfolio of plate heat exchangers to cover the widest range of needs. With the experience we have gained along the way, we can match you with your optimal solution.
What are the benefits of a plate and frame heat exchanger?
Other than its heat transfer efficiency, one of the great benefits of a plate-and-frame heat exchanger is its modularity. If your heating/cooling needs change in the future, you can easily accommodate the new requirements by adding or deleting plates within the frame.
What are the two sides of a heat exchanger?
Two liquid streams, referred to as the "hot side" and the "cold side," go into and come out of a heat exchanger (figure 1). As a result, there are four temperatures to consider when sizing the heat exchanger: hot side inlet, hot side outlet, cold side inlet and cold side outlet.
How to stop heat exchanger from leaking?
Generally, it is easier to prevent a heat exchanger from leaking than to stop a leak once it occurs. An important point to remember is that a plate-and-frame heat exchanger is not tightened to a torque specification but rather to a platage dimension. Between each pair of plates is an elastomeric gasket that, as compressed, seals the area between the plates and prevents leakage. Picture a large heat exchanger with perhaps 600 to 700 plates, each with a gasket between them, and you can imagine how much compression will take place when you start to close the unit by tightening the tie-bars.
How to keep particles in suspension in heat exchanger?
Particles entering into the exchanger can potentially get caught in the plate channel, so it is important to ensure that no particulate larger than 0.0625" is allowed to enter the heat exchanger. If your liquids could contain larger particles, they should be removed with either a strainer or separator prior to their entering the exchanger. This is especially important if there is an open tank in the system where larger particles could be introduced. Increased velocity is not only important for efficiency, but also to help keep particles in suspension so they pass through the exchanger. Most plate-and-frame heat exchangers will allow particles 0.0625" or smaller to pass. For liquids containing larger particles than this, "wide-gap" plate designs are available.
How fast should a heat exchanger be?
A safe rule of thumb is to keep port velocity at the heat exchanger around 20 ft/sec. In addition, consider port liners of the same material as the plates, even on water applications. These liners, available in many different alloys, will protect the carbon steel head from erosion and corrosion in high flow, abrasive applications. As an example, in a sea (salt) water application, it would be common to use a carbon steel frame with titanium port liners and plates. This practice ensures that any components in contact with the seawater would be constructed of the corrosion-resistant titanium.
Why use a PHE in a cooling tower?
For instance, if the PHE is to be used in conjunction with a cooling tower, it should be designed for the water treatment chemicals being used to treat the tower water. Also, it is easier to prevent a heat exchanger from leaking than to stop a leak once it occurs.
What information is needed to size a heat exchanger?
The minimum information needed to size the heat exchanger for both the hot and cold sides are: fluid names, flow rates, inlet temperature, outlet temperature, operating pressures and maximum pressure drop allowed across the unit. For fluids that are uncommon or proprietary, physical properties such as viscosity at inlet and outlet temperatures, thermal conductivity, specific gravity and specific heat will be needed. Most manufacturers have a design questionnaire available for you to use when collecting data for a heat exchanger application and would be eager to furnish you with a copy.
Overview
Design of plate and frame heat exchangers
The plate heat exchanger (PHE) is a specialized design well suited to transferring heat between medium- and low-pressure fluids. Welded, semi-welded and brazed heat exchangers are used for heat exchange between high-pressure fluids or where a more compact product is required. In place of a pipe passing through a chamber, there are instead two alternating chambers, usuall…
Evaluating plate heat exchangers
All plate heat exchangers look similar on the outside. The difference lies on the inside, in the details of the plate design and the sealing technologies used. Hence, when evaluating a plate heat exchanger, it is very important not only to explore the details of the product being supplied but also to analyze the level of research and development carried out by the manufacturer and the post-com…
Optimization of Plate Heat Exchangers
To achieve improvement in PHE's, two important factors namely amount of heat transfer and pressure drop have to be considered such that amount of heat transfer needs to be increased and pressure drops need to be decreased. In plate heat exchangers due to presence of corrugated plate, there is a significant resistance to flow with high friction loss. Thus to design plate heat exchangers, one should consider both factors.
Flow distribution and heat transfer equation
Design calculations of a plate heat exchanger include flow distribution and pressure drop and heat transfer. The former is an issue of Flow distribution in manifolds. A layout configuration of plate heat exchanger can be usually simplified into a manifold system with two manifold headers for dividing and combining fluids, which can be categorized into U-type and Z-type arrangemen…
See also
• Plate fin heat exchanger
• Heat transfer
• LMTD
External links
• Heat Exchangers at Curlie
• A list of published articles pertaining to plate heat exchangers
• A screening method for the optimal selection of plate heat exchanger configurations by J.M.Pinto and J.A.W.Gut, University of São Paulo, Brazil.