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 Integrated in cooling equipment, it is through the evaporation of the refrigerant that heat is withdrawn from the fluid that one wishes to cool or from the air of an enclosure that one wants to maintain at a low or negative temperature.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 QUIRI THERMAL EXCHANGES, EXPERT IN SHELL AND TUBE HEAT EXCHANGERS
Quiri Thermal Exchanges 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. Quiri Thermal Exchanges also provides heat exchanger parts and components, such as test rings or floating head accessories. With a cutting-edge knowledge of various heat transfer technologies, boilermaking and mechanical design, our experts are able to provide you with the most efficient tubular heat exchanger to meet your specific industry needs.
Return to Glossary Home Page
Return to Quiri Thermal Exchanges Home Page