Heat exchangers are designed with the purpose of transferring heat between two fluids without the fluids coming in contact. There are many different types and configurations of heat exchangers, the most common being, tube in tube, shell & tube and plate & frame. Each type of heat exchanger comes with its advantages and disadvantages with regard to their efficiency and suitability for different applications. In this article, we will explore these three types of heat exchangers and analyse their efficiency.
Tube in Tube Heat Exchangers
Tube in tube heat exchangers are known for being the simplest heat exchangers, with one fluid flowing through the smaller tube, the other flowing through the annular gap between the two tubes. Tube in Tube heat exchangers are best for processing highly viscous fluids, such as dips, chutney, fruit yoghurt or sewage and slurries. However, for processes where there are little to no particles, tube in tube heat exchangers are less efficient compared to other types of heat exchangers. This inefficiency is primarily due to the inner tubes producing only laminar flow, which significantly reduces the rate of heat transfer.
Shell & Tube Heat Exchangers
Shell & Tube heat exchangers consist of a series of tubes, called the tube bundle, with a larger outer tube call the shell, fluid is either heated or cooled as it flows through the inner tube bundle. The configuration allows for a significant surface area for heat exchange, making it highly effective for processes involving large temperature differentials and high-pressure applications. The turbulent flow within the tubes enhances heat transfer rates, leading to improved efficiency compared to simpler designs like tube in tube heat exchangers. Shell and tube heat exchangers are particularly well-suited for applications requiring efficient heat transfer and can handle a wide range of fluids, including those with particles or high fouling tendencies, making them a preferred choice in many industrial settings.
Plate & Frame Heat Exchangers
Plate and frame heat exchangers are known in the industry as being up to 5 times more efficient than other heat exchanger types. Plate heat exchangers consist of numerous thin, slightly parted plates that have large surface areas and small fluid flow passages for heat transfer. This design maximises the surface area available for heat transfer while maintaining a compact footprint. The corrugations create turbulent flow, significantly enhancing heat transfer rates and overall efficiency compared to other types of heat exchangers. Plate and frame heat exchangers are particularly effective in applications with moderate to low viscosity fluids and where space is a premium. Additionally, their modular design allows for easy expansion and maintenance, further boosting their operational efficiency. These attributes make plate and frame heat exchangers an excellent choice for a wide range of industries, including HVAC, food and beverage processing, and chemical processing.
The Dimpleflo® Advantage in Efficiency
Tubular heat exchangers are becoming a more favourable choice over plate and frame heat exchangers due to their significantly lower maintenance requirements. Developments in tubular heat exchanger technology has seen dimples or corrugations added on the inner and outer tubes to radically increase turbulence and as a result increase efficiency.
Teralba’s unique ‘dimple profile’ is used to increase turbulence of the product and service media. The increased turbulence results in a reduction of the total surface area arrangement for a specific duty and creates a high heat transfer coefficient without excessive pressure loss. In many situations, the type of heat exchanger selected is determined by the type of fluid being processed or the application in which the heat exchanger is being installed. This means that efficiency becomes one of many factors when selecting a heat exchanger.
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