Tube in Tube Heat Exchangers:
Double tubes heat exchangers are designed whereby one tube is centrally located within a larger tube. The double tube structure allows for unrestricted flow of product, making it an ideal heat exchanger for viscous products. Products flow through the inner tube, & the service fluid flows through the surrounding shell through the space between the two tubes.
Tubes in the tube heat exchanger are specially designed for heating or cooling low-medium viscosity products. The great advantage of tube-to-tube heat exchangers is being able to process products with fibers or particles without the risk of clogging.
The large diameters of the tubes ensure their free flow. This heat exchanger is dismountable, which makes mechanical cleaning possible. The AlfaVap In-Line is a multi-effect plate evaporator that fits into a single frame.
It is customized according to the need of the application, is compact, and minimizes the footprint. Simply plug and play unit, on-site installation saves time and is maintenance-friendly.
AlphaWap in-line is being used for sweeteners in the starch industry, coconut water, and clear juices. Special construction and corrosion-resistant material ensure its long service life.
To answer the question of what a tube is in the tube heat exchanger, let’s look at what are the different parts of this exchanger. The equipment consists of single tubes mounted inside an outers shell tube so that the product flows counter-currents through the inner tube, with the service mediums around it.
The diameters of the inner tube are smaller than that of the outer tube. The Inners tubes are placed inside the outer tube in a concentric circle type shape.
Tubular heat exchangers modules are normally connected in series and mounted on a frame. The product mediums insides the tube flows into the service medium in counter current. The product tube is corrugated, or it may be smooth. The shell tube is always smooth.
Its unique and compacted designs prevent thermal fatigue, increase efficiency, & reduce overall size. It is ideals for high temperatures, high pressure, & low flow applications.
The layout of tube-in-tube heats exchangers can be customized to fit available installation footprints or other customer requests. The use of flange connections allows these tubular heat exchangers to be separated to facilitate cleaning and maintenance tasks.
The design is being used by leading OEMs around the world and in the ever-growing wholesale replacement market. The simplicity of design and installation make this product ideal in both markets.
#3. Display Features
- Heat transfer rate up to 100,000 Btu/h (29 kW)
- Fluid flow up to 10 GPM (38 LPM)
- the Pressures up to 4,500 psi (310 bar)
- Work temperature up to 152 °C
- Reynolds can achieve tubular flow.
- Corrugated inner tube to give additional heat transfer area.
Working Principle of Tube Heat Exchangers:
The working principle of these heats exchangers is simple. A tube-in-tube heat exchanger can achieve a net countercurrents flow, which allows temperatures crossovers to be achieved so that the cold fluid can be heated above the hot fluid outlet’s temperatures.
The hot or cold liquid never comes into contact with the fluid that is heating or cooling it. The inner and outer tubes each hold hot or cold fluid. This method is known as the indirect heat transfers method. The fluid in the outers tube enters the fluid in the inner tube from the opposite end of the tube. This is called counter-flow or contraflow.
In tube heat exchangers find use in tube preheating and cooling sections where a direct steam injection heat exchanger is required. The heat exchangers on the preheat & cooling sections are by indirect heat transfer method, but the final heating is done by directly injecting steam into the product, which is known as Direct Steam Injection or Direct Steam Infusion.
Types of Tube Heat Exchangers:
There are three types of the tube in tube heat exchangers for a variety of applications as follows:
#1. Sanitary Double Tube Heat Exchangers
The sanitary tube in tube heat exchangers consists of two tubes, one inner and one outer coiled. This sanitary model is designed to meet the pharmaceutical industry’s high-quality requirements and hygienic standards. There is no risk of cross-contamination between the product and the working fluid.
#2. Industrial Double Tube Heat Exchangers
In this design, the inner tube is corrugated to reduce heat transfer and less fouling. As the name suggests, it is designed for industrial applications.
#3. Industrial Double Tube Heat Exchangers With Removable Tube
In this type of heat exchanger, the inner tube is removable, which allows for easier and faster inspection/cleanup resulting in reduced operational downtime required for high-fouling products.
The concentric tube geometry makes it easy to work with particulate liquids without worrying about blockages impeding the flow of the tube product. Special corrugated tubes make them more efficient than similar smooth tube heat exchanger designs.
Advantages of Tube Heat Exchangers
- High thermal efficiency due to corrugated tubes
- Easy to clean
- Low maintenance
- All hygienic fittings
- High particle capacity
- Resistant to fouling
- Flexibility in building materials from carbon steel to special alloys
- Can handle high viscosity product
- Meets industry standards required for CIP cleaning. Minimum 1.5 meters per second velocity
Disadvantages of Tube Heat Exchangers:
- Requires more space due to less heat exchange surface area
Applications of Tube Heat Exchangers:
- Tube to tube heat exchangers are generally applied for:
- Multi-phase liquids and solutions
- High thermal stress
- Steam Condensing
- Sealed Cooling
- WFI (Water for Injection)
Tube in tube heat exchangers is specifically designed for use in water-cooled condensers, water chillers, the paper industry, and water source heat pumps.