As the two most common heat exchangers, plate-and-frame and shell-and-tube designs, both have a lot to offer when you want to heat or cool a product during processing. Heat exchangers work by transferring heat from one media to another via tubes or plates.
In some applications, however, plate heat exchangers (PHE) have several advantages over shell-and-tube designs. In this post, we discuss application requirements that make PHE the right choice.
The greater surface area for heat transfer in PHEs makes them more efficient than shell-and-tube designs.
In the following sections, we will show you how a plate heat exchange is the P.E.R.F.E.C.T. choice for your next heat-transfer solution.
Due to the lower area required with a PHE, PHE designs typically have an overall pressure drop substantially lower than a tubular designed for the same specifications. This lower pressure drop adds to the overall energy efficiency of a PHE over a tubular heat exchanger.
Plate heat exchangers are up to five times more efficient than shell-and-tube designs. In many cases, you can utilize more heat by replacing existing shell-and-tube models with compact plate and frame heat exchangers.
The series of plates in a plate-and-frame heat exchanger creates gasketed spaces between plates. These spaces alternate between two fluids—one hot and one cold.
The design delivers very high heat transfer efficiency because the plates create a surface area that's much larger than shell-and-tube designs that would fit in the same space.
Typically, a plate heat exchanger is the right choice because they’re the most efficient and least expensive option. Plate heat exchangers are up to five times more efficient than shell-and-tube designs.
Higher heat transfer coefficients can be attained due to the corrugated plates and higher velocities
Closer temperature approaches due to pure counter current flow, allowing for more heat transfer
Higher amount of regeneration possible due to these closer temperature approaches
Removing and reconfiguring plates allows plate heat exchangers to adapt to specific heat transfer requirements, enhancing their maintenance and efficiency. The series of gaskets in a plate-and-frame heat exchanger creates spaces and formed flow paths between plates. These spaces alternate between two fluids—one hot and one cold.
The heat transfer coefficient describes how effectively the two designs transfer heat (PHE vs. Shell and tube, Fig. 2, below). The coefficient is a multiplier in the heat transfer equation, so a higher number means more heat transfer occurs. PHE’s achieve their improved heat transfer coefficients while having a much smaller footprint and lower weight than their shell-and-tube counterparts.
| Overall Heat Transfer Coefficient - U - | ||||
|---|---|---|---|---|
| Liquid-to-Liquid Heat Transfer | Heat Transfer Coefficient W/(m2 K) | Btu/(ft2 °F h) | ||
| Shell and Tube | 150-1200 | 25-200 | ||
| Plate and Frame | 1000-4000 | 150-700 | ||
Heat transfer inside a heat exchanger results in temperature changes in both fluids, lowering the temperature of the warmer fluid and raising the temperature of the cooler fluid.
Fluid properties partially determine the type of heat exchanger for the application.
High-quality plate-and-frame heat exchangers can operate efficiently for ten years without maintenance. Plates are easy to access for inspection or cleaning in place. Cleaning intervals depend on amounts of fouling or scaling.
Plate heat exchangers are much easier to maintain and operate than shell-and-tube because they're easier to take apart and inspect. You can easily remove plates for service or repair, whereas shell-and-tube models are more labor-intensive and harder to access internally.
Product buildup or scale coating on surfaces reduces the heat exchanger's thermal efficiency. Because of plate and frame exchangers' smaller, modular design, they are faster and easier to clean than larger shell-and-tube units.
The surface area in a plate heat exchanger is made compact because of the stacking of the plates. This stacking reduces the footprint of the plate heat exchanger vs a tubular heat exchanger even for units with the same amount of surface area. Making the compact size of a plate heat exchanger also important to applications with tight spaces. Smaller footprint and greater scalability make plate heat exchangers the best choice in applications where space is limited or scale flexibility is required.
If a need to expand heat transfer capacity is likely, plate heat exchangers are an excellent choice because you can change capacity easily by adding or removing plates. Planning for future expansion includes sizing of the plate heat exchanger for its initial duty plus space allowance for plate capacity and easy field installation. Shell-and-tube capacities cannot be modified.
A plate heat exchanger is the lowest cost option because it can achieve high heat transfer coefficients — with pure counter current flow — giving the most efficient heat transfer and lowest surface area. Maintenance cost is also reasonably low, especially compared to scraped-surface heat exchangers. The main expense is the replacement of gaskets and, occasionally, of plates.
The close temperature approach, meaning a cold fluid being heated to a temperature that is very close to the temperature of the entering hot fluid, allows more regeneration and heat recovery, making a plate heat exchanger a good option. Smaller temperature variances between product and media also prevent burn-on in products with moderate to high sugar or protein content.
Capital costs can include shipping, handling, installation, and maintenance over the unit's lifetime.
Plate and frame heat exchangers can be adapted for various product viscosities.
When a PHE has difficulty handling viscous products, it's typically because it was initially designed for use with fluids of very low viscosity but later used with highly viscous products.
PHE can be adapted to more viscous or particulate products by exchanging standard-gap (3-5mm) chevron plates for wide-stream plates for fine particulate (same gap but fewer contact points than chevron plates) or wide-gap (up to 8mm) plates that can process larger particulates and higher viscosity.
| Average Gap | Particle Size | Fiber Length | Pulp % | Viscosity CPS | |
|---|---|---|---|---|---|
| Typical Industrial Plate | 2.4-3.95mm | Dia 0.5mm | 1mm | 2 | 2500 |
| Typical Sanitary Plate | 3.95mm | Dia 0.5mm | 1mm | 3 | 5000 |
| Low Contact Point Plate | Up to 8mm | Dia 0.5mm | 5mm | 7 | 1000 |
Advantages
Disadvantages
QCHE © 2025 Copyright | All Rights Reserved
