This article will give an in-depth discussion about plate heat exchangers.
This article will give a better understanding of:
A plate heat exchanger (PHE) is a compact type of heat exchanger that utilizes a series of thin metal plates to transfer heat from one fluid to the other. These fluids are typically at different temperatures.
This section will discuss how a plate heat exchanger works.
The PHE device makes use of the principle of thermodynamics. In these exchangers, each plate has a confined, concave tubular shell. The plates are arranged in such a way that thin channels that are rectangular in shape are developed to change heat through partial pieces.
Between these twisted and narrow channels, the operating fluid flows. The plates of this exchanger are girdled by gaskets to control the fluid flux. These gaskets are arranged in such a way that only one type of liquid (like a canvas which is being toasted) distributes on one plate, and another fluid (like hot water) distributes on the coming plate. The following figure presents two conterminous boards.
After this arrangement, the cold and hot fluids alternatively suffer the plate, whereby a heat exchange takes place. The plates have a large face area; thus, they offer an excellent heat transfer rate than tubular heat exchangers.
As illustrated above, the cooling fluid bay (blue) is on the bottom, the cooling fluid outlet on the top, and again for the hot fluid outlet (red). The cool fluid flows in an upward direction and the fluid to be cooled overflows in a downcast direction, transporting the heat through the plates. After completing this process, the heating medium is eventually cooled, and the cooling medium is toast. The heat transfer principle and design of the plate heat exchangers is characterized by their compact design, low heat loss, a wide range of operations, flexible operation, high heat transfer effectiveness, small installation and drawing functions.
The operation of a plate heat exchanger involves:
Some pressure drop is necessary though it should be kept close to the designed value. Thus, further energy is demanded to get the asked inflow through the equipment. If there is a reduction in the device’s capability to hold the asked temperatures together with increased pressure on the media, it means that fouling or clogging has occurred. Measure the inflow rate if possible, and compare it with the specified for the actual inflow rate:
The device must be placed on a hard surface bottom. According to space conditions, 1.5 m from the walls also ensure enough space around the plate device. This is extremely important when servicing the unit i.e. renewal of plates or tightening of the plate package. The quantum of free space needed is stated on the assembly delineation.
It is important that the compressed dimension is checked against the delineation before the pipes are connected if the plate device has connections on the portable plate. It's necessary to leave free space around the device to give access and allow for the possibility of future services. The confines suggested are 1.5m to give good working conditions during installation as well as conservation and service.
Before launch-up, check that all the tensing bolts are forcefully tensed and that the plate pack has correct measures. The start-up of the heat exchanger must be accepted slowly and easily to avoid any pressure shocks/water forging, which might damage the outfit or cause leakage.
The following considerations are important:
When operating plate heat exchangers:
The following general procedure is important:
The following precautions are important:
The following general procedure is to be followed if the unit must be disconnected:
The different designs of plate heat exchangers include:
The upper part that is fixed between the supporting column and the fixed plate where the pressure plates and the exchanger plates are connected.
The fixed plate is an abecedarian part of the plate heat exchanger. As the name of this plate represents that it's a fixed frame plate. Generally, the heat exchanger pipes and the fixed plates are connected together.
This is a non-portable part of the plate heat exchanger. The guiding bar and carrying shaft are attached to this part
The plate heat exchanger has a mobile pressure plate frame attached with the exchanger carrying shaft. The frame can compress the exchanger’s plates.
This part guides the pressure plate and heat exchanger plates over.
It's used to compress the frame corridor of the plate pack. It possesses tensing nuts, tensing washers, and tensing bolts.
The quilting of plates installs between the pressure plate and the fixed frame plate. This plate pack compresses by tensing the screws fastened between the two plates. The gaskets cover the plates to regulate the flux.
The types of gaskets used in plate heat exchangers include:
The slit-in gasket is especially recommended for those operations where frequent relief of the gasket is demanded. Furthermore, without the cement, cement odor is reduced. The slit-in type gasket is suitable for operations similar to water treatment or food processing.
Generally, EPDM gaskets are recommended for either high temperature or aggressive fluid operations. EPDM gaskets are high quality, unlike rubber gaskets that lose elasticity as time passes.
PTFE Cushion Gaskets are generally useful in applications where conventional synthetic rubber would be limited due to the cattiness of the fluid being handled. Due to their chemical resistance, PHE can be applied in a wider variety of operations. The TCG gasket does not bear a strong tightening collar during the assembly of the unit due to its elastic core. Therefore, it reduces the pitfalls of plate distortion by over tightening. A TCG gasket can only be useful for one side, if the non corrosive fluid is running on the other side where a conventional gasket can be used.
The types of plate heat exchangers include:
The types of plate heat exchangers include:
This type of heat exchanger makes use of top quality gaskets and construction. This gasket stops leakage by sealing the plates. Plates of this exchanger can be easily removed for the relief, expansion, or cleaning of the plates, which significantly reduces costs.
The brazed plate heat exchanger is applied in many refrigeration and artificial operations. Since the pristine-brand plate is brazed with bull, it has excellent erosion resistance. These types of plate heat exchangers are compact in design and their performance is effective, which makes them an economically superior option.
Advantages of Brazed plate heat exchanger:
The operation of these heat exchangers is analogous to gasket heat exchangers, but the plates of these heat exchangers are welded together (with each other). These have excellent continuity and are suitable for transporting hot fluids and sharp substances. These exchangers have welded plates; thus, one can’t clean the plate mechanically like plate and frame heat exchanger.
This type of heat exchanger is a combination of two types of heat exchangers which are: gasketed plates and welded plates. It has a brace of two plates welded together and also a gasket with another brace of plates so that one fluid can flux through the welded part and the other fluid can flux through the gasketed part. This arrangement of the plate exchanger makes it easy to repair. Thus, this exchanger can also transfer more important fluid on the other. These exchangers have little trouble with fluid loss.
The heat exchanger in which the plates produce a frame is known as plate and frame heat exchanger. The plate and frame heat exchanger (PHFE) contains corrugated plates in the frame. Due to this construction, the PFHE produces high wall shear stress and turbulence that leads to high stain resistance and a high rate of heat transfer.
This heat exchanger has gaskets. In addition to the sealing effect, the gasket also guides the flux and is installed along the groove on the plate edge. The plate and frame heat exchanger is used to change heat between liquid, and liquid at medium to low pressure. A plate and frame heat exchanger can be safely used at high temperature and pressure without a gasket.
Plate and frame heat exchanger characteristics:
The major components of plate heat exchangers and their functions include:
A single plate heat exchanger can contain an outside of 700 plates. As the plate pack compresses, the holes in the plate’s corners produce a constant passage or manifold that allows fluid to flow through the plate pack and exit the device. The space between the thin plates of the heat exchanger makes a tight channel that alternately traverses by cold and hot fluids and offers truly small resistance to heat transfer.
Plate element pattern types include:
The corrugated pattern is also called the marsh board pattern. It has lower substance contact points between plates and allows for liquids with fiber or sludge contents to flux easily without blockage.
The “herringbone" pattern was named as the V-shaped press grooves act the bones of a herring.
There are a number of contact points made by piling the V-shaped pressed plates, and then turning them 180° in an interspersing pattern. This ensures the resistance of high pressure, and also the complex flux channels formed by the V- shaped press grooves get high heat transfer performance. Likewise, including the dropped heat transfer resistance due to the thinner plate results in heat transfer performance three to five times more advanced than that of S&T heat exchangers.
There are various types of plates in plate heat exchangers which will be discussed below:
This chapter will discuss the applications, advantages and maintainability of plate heat exchangers.
Applications of plate heat exchangers include:
As much as plate heat exchangers may have drawbacks such as having high pressure drop and heat resistance of the sealing material, which limits the operating temperature, there are several advantages which outweigh the drawbacks. Some of the advantages of the plate heat exchanger include:
The steps to follow in the general maintenance of a plate heat exchanger are listed below:
The first step is to disassemble the plate heat exchanger.
Opening procedure:
The plates are designed for both homemade cleaning and cleaning-in- place operations. The user must make sure that the unit has been de-pressurized, locked out, and drained before disassembly. Homemade cleaning is typically fulfilled by washing the plates with a soft non essence encounter, water, and cleaning result. It's recommended to lay the plate on a flat face during encounter cleaning to avoid the threat of bending the plate. However, care must be taken to remove all debris from the gasket sealing shells when the heat exchanger is reassembled, if the heat exchanger is heavily fouled.
Steps for Manual Cleaning of Plates:
Steps for Cleaning-in-Place (CIP):
During this examination, it’s vital to test and check the plates for cracks and perforations throughout the equipment. First, visually check the heat exchanger plate for any egregious blight. Pay close attention to where the plates come in contact with one another. If perforations are present, they can generally be found at the contact point of where the plates meet. To prop in a visual examination, use a light to help pinpoint other blights. A visual and light examination may not reveal all of the blights of a heat exchanger plate.
Once the gasket plates are tested, it’s time to install them. This will require mechanical professionals to install gaskets onto the plates. Inspect the gasket groove to ensure it’s clean and removed of all debris. When it comes to the flow pass, there are two types: parallel or diagonal. Each flow path depends on the type of plate model and can be further illustrated in the technical drawing associated in your plate manual.
Verify each unit is functioning properly.
It has been seen that the PHE offers numerous advantages over other types of heat exchangers. However there is a variety of plate heat exchangers that are suitable in different applications and each having its own advantages and disadvantages. Therefore one must be aware of the specifications when choosing a heat exchanger for a particular application. The PHE must be generally well maintained for a long lasting life.
Heat exchangers are pieces of equipment used to transfer heat between two or more fluids. This process usually involves abundant working or utility media such as water or air that rejects or absorbs heat from a more valuable fluid such as crude oil, petrochemical feedstocks, and fluidized products...
A shell and tube heat exchanger (STHE) is a type of heat exchanging device constructed using a large cylindrical enclosure, or shell, that has bundles of perfectly spaced tubing compacted in its interior. Heat exchanging is the transfer of heat from one substance or medium to a similar substance or medium...
Air cooled chillers are refrigeration systems that cool fluids and work in tandem with the air handler system of a facility. Air cooled chillers are types of chillers that rely on the use of fans to reject heat outside the...
A chiller is a cooling mechanism designed to produce fluids that can lower temperatures by removing heat from the fluid. The type and use of a chiller depends on the required temperature and kind of refrigerant, which can be a liquid or a gas...
Cooling towers are specialized heat exchangers that remove heat from water mainly by means of latent heat loss from evaporation while coming into contact with an airstream. Aside from evaporative cooling, water is also cooled by sensible heat transfer due to the temperature difference between air and water...
A glycol chiller is a chilling system that uses a percentage of glycol mixed with water to create extremely low temperatures far beyond the freezing point of water. The two types of glycol are ethylene glycol based or propylene glycol based...
Laser cooling is a multi-process that includes a number of techniques in which atomic and molecular samples are cooled down to a temperature near absolute zero. These techniques depend on...
Open loop cooling tower makes use of direct contact with the air in order to cool down the water. It is essentially a heat exchanger. In these types of cooling towers, there is the partial heat transfer due to heat exchange between...
A water chiller, or chilled water system, is a type of refrigeration system which uses water as a secondary refrigerant. They are used for larger, more complex, heating, ventilating, air conditioning, and refrigeration (HVACR) applications...