Heat Flow Technology

A shell and tube heat exchanger is a class of heat exchanger designs.^[1][2] It is the most common type of heat exchanger in oil refineries and other large chemical processes, and is suited for higher-pressure applications. As its name implies, this type of heat exchanger consists of a shell (a large pressure vessel) with a bundle of tubes inside it. One fluid runs through the tubes, and another fluid flows over the tubes (through the shell) to transfer heat between the two fluids. The set of tubes is called a tube bundle, and may be composed of several types of tubes: plain, longitudinally finned, etc.

Two fluids, of different starting temperatures, flow through the heat exchanger. One flows through the tubes (the tube side) and the other flows outside the tubes but inside the shell (the shell side). Heat is transferred from one fluid to the other through the tube walls, either from tube side to shell side or vice versa. The fluids can be either liquids or gases on either the shell or the tube side. In order to transfer heat efficiently, a large heat transfer area should be used, leading to the use of many tubes. In this way, waste heat can be put to use. This is an efficient way to conserve energy.

Heat exchangers with only one phase (liquid or gas) on each side can be called one-phase or single-phase heat exchangers. Two-phase heat exchangers can be used to heat a liquid to boil it into a gas (vapor), sometimes called boilers, or to cool the vapors and condense it into a liquid (called condensers), with the phase change usually occurring on the shell side. Boilers in steam engine locomotives are typically large, usually cylindrically-shaped shell-and-tube heat exchangers. In large power plants with steam-driven turbines, shell-and-tube surface condensers are used to condense the exhaust steam exiting the turbine into condensate water which is recycled back to be turned into steam in the steam generator.

They are also used in liquid-cooled chillers for transferring heat between the refrigerant and the water in both the evaporator and condenser, and in air-cooled chillers for only the evaporator.

Evaporator
An evaporator is a heat exchanger that converts the sensible or latent heat of one fluid into the latent heat of vaporization of another.
If it is used to convert water or an aqueous solution from the liquid state to the vapor state, it is generally referred to as an evaporator. If it is used in a process at the bottom of a distillation column, whether the steam is water or not, it is called a reboiler. When used neither in steam production, nor as part of a distillation process, it is rather identified as a vaporizer.
When an evaporator is used in a cogeneration plant to produce primary or secondary steam, it is a steam generator. Integrated in cooling equipment, it is through the evaporation of the refrigerant that heat is withdrawn from the fluid that one wishes to cool or from the air of an enclosure that one wants to maintain at a low or negative temperature.
OPERATION OF THE TUBULAR EVAPORATOR
The evaporator is a heat exchanger working with a fluid whose pressure and temperature conditions allow it to pass from the liquid state to the gaseous state.
As a specialist in the design and manufacture of shell and tube heat exchangers, Quiri develops tubular evaporators.
These are made up of a set of closely spaced tubes, arranged in parallel (called a tube bundle) and grouped together in the same cylindrical body (called a shell). The type, arrangement, material and dimensions of the tubes are carefully chosen to allow the fluid to transfer heat very well.
Two types of shell and tube evaporators can be distinguished:
Shell and tube flooded evaporators
In the shell and tube flooded evaporator, the fluid to be evaporated is located outside the tubes. The tube bundle is immersed in the saturated fluid, contained on the shell side. Boiling can then occur by nucleation or by film, depending on the heat transfer situation. By acting on the liquid level, it is possible to ensure operating conditions and a steam overheat of up to 5 C.
Shell and tube dry expansion and thermosyphon evaporators
Shell and tube dry expansion and thermosyphon evaporators work with the fluid to be evaporated circulating inside the tubes. In the case of dry expansion, it is supplied by a thermostatic expansion valve, allowing it to regulate the overheat. Used in the field of industrial refrigeration, the refrigerant circulates inside the tubes (sometimes with improved geometry) to improve transfer performance and increase the compactness of the heat exchangers. Thermosyphon evaporators are more often used in distillation processes and are located at the bottom of the column with a manometric head, allowing recirculation.
IMPORTANCE OF EVAPORATORS
As evaporators allow the transfer and removal of heat from the substance to be cooled, they are essential for various industrial applications, especially in refrigeration and air conditioning processes, but also in power generation and some chemical and petrochemical processes.
Shell and tube evaporators are available in a wide variety of sizes and shapes and can be classified according to different criteria, such as the type of construction, the  refrigerant supply method or the application.
MORE ABOUT HFT EXPERT IN SHELL AND TUBE HEAT EXCHANGERS
HFT is an expert company in the design and manufacture of shell and tube heat exchangers. For many years, our specialists have been designing condensers, coolers, tubular evaporators and other industrial heat exchangers for the nuclear, energy and industrial  refrigeration sectors. HFT  also provides heat exchanger parts and components, such as test rings or floating head accessories.

• A choice of Copper or 90/10 Cupro-Nickel Tubes.
• Naval brass tube plates.
• Aluminium shell
• Cast iron headers.
• Leak detection ring – standard on 2700 & 2800 Series. (Available for 2300 and 2500 Series if required)
• Nitrile seals. (Viton seals are available for applications where operating temperatures > 100ºC)
• Manufactured in England
• Short delivery times available on many of our oil coolers

• Duty range - 3kW to 750kW (subject to flow rate and temperatures)
• Working Pressure (Oil) - 20 bar to 30 bar (Depending on Size)
• Working Pressure (Water) - 10 bar