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 and efficient device designed to facilitate the exchange of heat between two fluids, typically at different temperatures, using a series of thin metal plates.
This section delves into how plate heat exchangers operate.
PHEs work based on thermodynamic principles. Each plate is paired with a specific concave tubular shell. The arrangement creates narrow, rectangular channels, enabling effective heat transfer through these segmented regions.
Fluids flow through these narrow channels encased by gaskets, which help control the fluid movement. These gaskets ensure that one fluid type (potentially a heated canvas) passes over one plate while another fluid (like heated water) moves over the adjacent plate. The visual below displays two neighboring plates.
In this arrangement, cold and hot fluids alternate over the plates, enabling heat transfer between them. The extensive surface area of the plates enhances the rate of heat transfer compared to tubular heat exchangers.
As demonstrated in the diagram, the cold fluid inlet (blue) is positioned at the bottom, with the outlet at the top, while the hot fluid outlet (red) is also strategically located. This setup allows the cooler fluid to rise as the warmer fluid descends, transferring heat across the plates. This mechanism results in cooling of the heating medium and the warming of the cooling medium. Plate heat exchangers are celebrated for their compact design, efficient heat transfer, adaptability, and ease of installation and maintenance.
Operating a plate heat exchanger involves several steps:
Maintaining a specified pressure drop is critical. Excess energy may be necessary if it deviates from the design, signifying potential fouling or clogging. Monitor the flow rate against specifications to uncover discrepancies:
Install the device on a stable, level surface. Ensure at least 1.5 meters of clearance from walls for maintaining tasks like replacing or tightening plates. The installation manual specifies required free space.
Before pipe connections, confirm compressed dimensions match specifications if extensions are on a removable plate. Allow 1.5 meters of clearance around the device for optimal working conditions during installation and maintenance.
Ensure all bolts are secure and the plate pack is correctly assembled before startup. Initiate operation gradually, avoiding pressure shocks or water hammer to prevent equipment damage.
Key points include:
Consider these aspects when operating plate heat exchangers:
Employ the following essential procedure:
Follow these precautions:
Steps for disconnecting the unit include:
Plate heat exchangers (PHEs) are high-efficiency heat transfer devices used extensively across HVAC systems, chemical processing, food and beverage production, power generation, and other industrial applications. Their design enables effective heat exchange between two or more fluids, typically liquids or gases, without mixing. To optimize their performance and functionality for different operating conditions, plate heat exchangers are available in a variety of configurations and materials. Below, we explore the essential design components and variations, highlighting why plate heat exchangers are the preferred solution for compact, cost-effective, and versatile thermal management.
The carrying beam, located in the upper section of the plate heat exchanger, is secured between the supporting column and the fixed plate. This critical component supports both the pressure plates and the heat exchanger plates, facilitating the proper alignment and distribution of pressure during operation. Ensuring structural integrity, the carrying beam helps maintain consistent heat transfer efficiency and system reliability.
The fixed plate acts as a stationary frame plate, forming the backbone of the plate heat exchanger. Typically constructed from highly durable stainless steel or other corrosion-resistant materials, the fixed plate is designed to withstand high pressures and temperatures. Heat exchanger pipes are often welded or bolted to this part, ensuring secure fluid connections and optimal operation over extensive cycles of use.
This robust, stationary component enhances the frame’s stability. It features attached guiding bars and a supporting shaft, which contribute to the precise positioning of the plate pack and facilitate maintenance. The support column is essential for heavy-duty operations where vibration resistance and longevity of the plate heat exchanger are critical.
An integral part of plate heat exchanger design, the movable pressure plate frame is connected to the carrying shaft. It enables the uniform compression of the stack of exchanger plates, ensuring proper plate-to-plate contact. This compression is fundamental for leak-free operation and consistent thermal transfer, making the pressure plate indispensable in both maintenance and overall thermal performance.
The guiding bar is a precision-engineered component that ensures smooth movement and precise positioning of both the pressure plate and the exchanger plates. Its design improves assembly, maintenance, and uniform distribution of compressive forces, extending gasket life and minimizing operational wear.
The tightening unit, often consisting of tensioning nuts, washers, and bolts, is used to apply and maintain uniform compression on the frame corridor of the plate pack. Proper tightening is crucial in preventing leaks and maintaining the integrity of gaskets and plates, especially during rapid thermal cycling or when processing aggressive fluids.
Gaskets play a vital role in the performance and safety of plate heat exchangers. Installed between the pressure plate and the fixed frame plate, these sealing elements ensure tight, leak-free operation by directing the flow along prescribed paths and preventing cross-contamination between media. Various compounds—such as Nitrile (NBR), EPDM, Viton, and PTFE—are selected based on chemical compatibility, temperature tolerance, and resistance to aging or compression set.
The types of gaskets used in plate heat exchangers are:
The slit-in gasket—often referred to as the “clip-on gasket”—is engineered for rapid replacement and minimal downtime. This glue-free design is ideal for industries demanding frequent sanitation or inspection, such as water treatment, dairy processing, or pharmaceuticals. Additionally, these gaskets reduce odors associated with adhesive application and minimize residual contaminants.
Ethylene propylene diene monomer (EPDM) gaskets are recommended for processes involving high temperatures or aggressive chemicals. EPDM gaskets retain elasticity and sealing performance far longer than standard rubber gaskets, making them ideal for heat exchanger operations where reliability and resistance to steam, glycol, or acidic cleaning agents are necessary.
PTFE (Polytetrafluoroethylene) cushion gaskets are engineered for highly corrosive or chemically aggressive fluid media, outlasting typical synthetic rubber alternatives. Their elastic core requires less tightening torque, minimizing the risk of heat exchanger plate deformation. PTFE gaskets are commonly used in petrochemical processing, pharmaceutical manufacturing, and any processes requiring the highest standards of chemical resistance. Generally, a TCG gasket is placed on one side with a conventional gasket on the other when one stream is corrosive and the other is non-corrosive.
Plate heat exchangers are available in distinct types, each tailored for specific industrial, commercial, or residential thermal applications. Understanding their operating principles and practical benefits is important for selecting the best solution based on heat transfer efficiency, ease of maintenance, chemical compatibility, and installation constraints.
This type of heat exchanger leverages high-performance gaskets to seal and direct fluid between the plates. The design allows for quick and convenient removal of plates, supporting fast relief, expansion, or deep cleaning to manage fouling or routine maintenance. Gasketed plate heat exchangers are commonly specified in HVAC, district heating and cooling, chemical plants, and food and beverage processing due to their versatility, serviceability, scalability, and overall energy efficiency.
When selecting a gasketed plate heat exchanger, important buying factors include plate material compatibility (such as stainless steel or titanium), gasket compound resilience, maximum allowable pressure drop, and ease of disassembly for CIP (clean-in-place) operations.
Brazed plate heat exchangers are compact yet highly efficient, with plates permanently bonded using copper or nickel brazing for enhanced corrosion resistance and thermal stability. These heat exchangers are ideally suited for refrigeration systems, hydronic heating, oil cooling, and small-scale process applications where space is limited and maintenance intervals are long. Their all-metal construction enables operation at higher temperatures and pressures compared to gasketed designs.
Advantages of brazed plate heat exchangers include:
Welded plate heat exchangers use plates that are either laser- or spot-welded together, eliminating the need for gaskets and allowing for operation under severe temperatures, elevated pressures, or when handling aggressive, fouling, or abrasive fluids. These plate heat exchangers are prevalent in petrochemical, pulp and paper, power generation, and process industries. However, please note that welded construction can limit mechanical cleaning options; thus, chemical cleaning is often recommended for long-term fouling management.
Semi-welded plate heat exchangers combine the benefits of both gasketed and welded designs. Alternating pairs of welded and gasketed plates form channels, making these exchangers well-suited for cooling tasks involving ammonia, aggressive chemicals, or fluids prone to leakage. The hybrid solution eases maintenance procedures on the gasketed side, allowing for regular inspection and cleaning, while the welded side withstands more corrosive or high-pressure media streams. This makes them ideal for demanding process cooling, chemical mixing, or ammonia refrigeration duties.
Plate and frame heat exchangers consist of a series of corrugated plates mounted within a rigid frame, optimizing surface area for maximum heat transfer between fluids at controlled pressures. The corrugated design increases turbulence, enhancing wall shear and reducing risk of fouling. These exchangers are common in building services (such as district heating, cooling, or swimming pool heat recovery), food processing, pharmaceuticals, and other critical process industries where hygiene, heat transfer rate, and reliable maintenance are paramount.
This heat exchanger features gaskets that both seal and route the working fluids via grooves along the plate edges. Standard plate and frame exchangers are ideal for medium-pressure and moderate-temperature applications, but can be adapted for higher demands by switching to welded or semi-welded versions.
Features of plate and frame heat exchangers include:
For facility engineers and maintenance professionals, factors such as ease of cleaning, service intervals, and compatibility with CIP (clean-in-place) systems are critical when selecting a plate and frame heat exchanger.
The key components of plate heat exchangers and their respective functions are:
A single plate heat exchanger can accommodate up to 700 plates. As the plate stack is compressed, the corner holes in each plate form a continuous pathway or manifold, enabling fluid to move through the plate stack and exit the exchanger. The narrow gaps between the plates create a series of channels where hot and cold fluids flow alternately, resulting in minimal resistance to heat transfer.
Types of plate element patterns include:
The corrugated pattern, also known as the marsh board pattern, features reduced contact points between plates. This design facilitates the smooth flow of liquids containing fibers or sludge, minimizing the risk of blockages.
The "herringbone" pattern is named for its V-shaped press grooves, which resemble the bones of a herring.
By stacking V-shaped pressed plates and rotating them 180° in an alternating pattern, numerous contact points are created. This arrangement enhances resistance to high pressure and generates complex flow channels due to the V-shaped grooves, leading to superior heat transfer performance. Additionally, the reduced heat transfer resistance from the thinner plates results in heat transfer efficiency that is three to five times greater than that of S&T heat exchangers.
Different types of plates used in plate heat exchangers are outlined below:
This chapter will cover the applications, benefits, and maintenance of plate heat exchangers.
Plate heat exchangers are used in the following applications:
Although plate heat exchangers may have some drawbacks, such as high pressure drops and limitations on operating temperature due to the heat resistance of the sealing materials, their advantages often outweigh these issues. Some benefits of plate heat exchangers include:
The following steps outline the general maintenance procedures for a plate heat exchanger:
The initial step is to disassemble the plate heat exchanger.
Procedure for opening:
The plates are suitable for both manual cleaning and cleaning-in-place (CIP) procedures. Before disassembly, ensure that the unit is fully de-pressurized, locked out, and drained. Manual cleaning generally involves washing the plates with a mild detergent, water, and a non-abrasive cloth. To prevent bending, it's advisable to clean the plates on a flat surface. When reassembling, especially if the heat exchanger has been heavily fouled, make sure to remove all debris from the gasket sealing surfaces.
Steps for Cleaning-in-Place (CIP):
Procedure for Cleaning-in-Place (CIP):
During the inspection, it’s crucial to examine the plates for any cracks or perforations. Start with a visual inspection of the heat exchanger plates, paying special attention to areas where the plates make contact with each other. Perforations are often found at these contact points. To aid in the inspection, use a light to help identify potential issues. However, note that visual and light inspections may not uncover all defects in the heat exchanger plates.
After testing the gasket plates, proceed with their installation. Mechanical professionals should attach the gaskets to the plates. Ensure the gasket grooves are clean and free from debris. The flow paths can be either parallel or diagonal, depending on the plate model. Refer to the technical drawings in your plate manual for detailed guidance on the flow paths.
Ensure that each unit is operating correctly.
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...