Marine heat exchangers are no different than non-marine heat exchangers except for the simple fact that they are found aboard ships. Heat exchangers can be used for a wide variety of uses. As the name implies, these can be used for heating as well as cooling. The two primary types of marine heat exchangers used aboard vessels in the maritime industry are plate, and shell and tube. Maintenance for heat exchangers prevents fouling and galvanic corrosion from dissimilar metals.
Though there are many more types of heat exchangers that are used shore side, plate and shell and tube heat exchangers are the most common type of heat exchangers found aboard ocean-going vessels.
Plate-type marine heat exchangers are designed with sets of multiple parallel plates that are compressed to form the main cooler unit. This type has a small footprint in comparison to other types of heat exchangers. The plates are designed in such a way that when placed next to each other they create passageways to the fluid to flow between the plates. Gaskets are placed around the edge of each plate in order to prevent the mixing of the two fluids. Due to the temperature and pressure constraints of the rubber used to make the gaskets plate type heat exchangers are used for low pressure, low temperature applications, under 290 psig (20 bar) and 300 degrees Fahrenheit (150 degrees Celsius). [1]
Shell and tube heat exchangers consist of a tube bundle which is placed inside the larger shell. [2] Due to this design these exchanger require twice the footprint of the plate heat exchanger in order to perform maintenance. Depending on the amount of cooling needed, shell and tube heat exchangers can be built in single or double pass configuration. The number of pass refers to the number of times the fluid in the shell passes by the fluid in the tubes. This is achieved by placing baffles in the shell that allow for the fluid to be directed.
Heat exchangers on board vessels are used throughout many system. Systems that use heat exchangers include lube oil, jacket water, steam systems and main seawater. The systems are often interconnected by heat exchangers in order to remove heat generated from running equipment from the engine room.
Heat generated due to friction is carried away from the engine in the motor oil. The motor oil flows through a heat exchanger, where the heat is passed to a central engine room cooling loop, before the heat is rejected to the ocean.
Heat generated an engine's cylinders is transferred to a jacket water cooling system through the cylinder wall. In addition to cooling the cylinder walls, jacket water is often found as an insulator between the exhaust header and the engine room. Jacket water cooling systems can be cooled by a central cooling water loop or can be cooled directly by seawater.
Unlike most systems with heat exchangers, steam is used to heat other systems. This is most common when a ship is left pierside for an extended period of time. The steam system will be used to prevent condensation and rusting of vital engine room components. These heat exchangers are most often shell and tube heat exchangers due to the high temperature and pressures often utilized in steam systems.
Seawater cooling is often the last stage of cooling on board a ship. These coolers are oftentimes the largest on board a vessel in order to ensure maximum heat transfer to the seawater. The seawater is then discharged overboard after passing through the coolers.
Maintenance of marine heat exchangers is important to ensure the small pathways in both types of coolers do not become fouled. Depending on the system different types fouling may occur. In oil based systems, an insufficient amount of cooling medium or inefficient flow of oil through the heater can cause the heater to become fouled. Seawater coolers can often become fouled due to marine life present in the water or due to galvanic corrosion if the correct safety measures are not taken to prevent such occurrences.
Regular maintenance of heat exchangers is important in order to maintain the heat exchanger's maximum efficiency. Sacrificial anodes are necessary in cooling systems to prevent galvanic corrosion. Anodes are often time made of Zinc and are replaced when they reach fifty percent wear. Shell and tube heat exchangers require tubes to be plugged upon the detection of a leak. This prevents the two liquids from mixing inside the heat exchangers. In order to perform regular maintenance on a plate type heat exchanger, the plate stack is separated and the plates a cleaned to improve heat transfer. [3]
A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contact. They are widely used in space heating, refrigeration, air conditioning, power stations, chemical plants, petrochemical plants, petroleum refineries, natural-gas processing, and sewage treatment. The classic example of a heat exchanger is found in an internal combustion engine in which a circulating fluid known as engine coolant flows through radiator coils and air flows past the coils, which cools the coolant and heats the incoming air. Another example is the heat sink, which is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant.
Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in cars, buildings, and electronics.
A boiler is a closed vessel in which fluid is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, central heating, boiler-based power generation, cooking, and sanitation.
Cupronickel or copper-nickel (CuNi) is an alloy of copper that contains nickel and strengthening elements, such as iron and manganese. The copper content typically varies from 60 to 90 percent.
An intercooler is a heat exchanger used to cool a gas after compression. Often found in turbocharged engines, intercoolers are also used in air compressors, air conditioners, refrigeration and gas turbines.
Water cooling is a method of heat removal from components and industrial equipment. Evaporative cooling using water is often more efficient than air cooling. Water is inexpensive and non-toxic; however, it can contain impurities and cause corrosion.
A fire-tube boiler is a type of boiler in which hot gases pass from a fire through one or more tubes running through a sealed container of water. The heat of the gases is transferred through the walls of the tubes by thermal conduction, heating the water and ultimately creating steam.
A shell and tube heat exchanger is a class of heat exchanger designs. 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 with a bundle of tubes inside it. One fluid runs through the tubes, and another fluid flows over the tubes 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.
Fouling is the accumulation of unwanted material on solid surfaces. The fouling materials can consist of either living organisms (biofouling) or a non-living substance. Fouling is usually distinguished from other surface-growth phenomena in that it occurs on a surface of a component, system, or plant performing a defined and useful function and that the fouling process impedes or interferes with this function.
A leak is a way for fluid to escape a container or fluid-containing system, such as a tank or a ship's hull, through which the contents of the container can escape or outside matter can enter the container. Leaks are usually unintended and therefore undesired. The word leak usually refers to a gradual loss; a sudden loss is usually called a spill.
A plate heat exchanger is a type of heat exchanger that uses metal plates to transfer heat between two fluids. This has a major advantage over a conventional heat exchanger in that the fluids are exposed to a much larger surface area because the fluids are spread out over the plates. This facilitates the transfer of heat, and greatly increases the speed of the temperature change. Plate heat exchangers are now common and very small brazed versions are used in the hot-water sections of millions of combination boilers. The high heat transfer efficiency for such a small physical size has increased the domestic hot water (DHW) flowrate of combination boilers. The small plate heat exchanger has made a great impact in domestic heating and hot-water. Larger commercial versions use gaskets between the plates, whereas smaller versions tend to be brazed.
A surface condenser is a water-cooled shell and tube heat exchanger installed to condense exhaust steam from a steam turbine in thermal power stations. These condensers are heat exchangers which convert steam from its gaseous to its liquid state at a pressure below atmospheric pressure. Where cooling water is in short supply, an air-cooled condenser is often used. An air-cooled condenser is however, significantly more expensive and cannot achieve as low a steam turbine exhaust pressure as a water-cooled surface condenser.
Economizers, or economisers (UK), are mechanical devices intended to reduce energy consumption, or to perform useful function such as preheating a fluid. The term economizer is used for other purposes as well. Boiler, power plant, heating, refrigeration, ventilating, and air conditioning (HVAC) uses are discussed in this article. In simple terms, an economizer is a heat exchanger.
An evaporator is a device used to turn the liquid form of a chemical substance, such as water, into a vapor.
An oil production plant is a facility which processes production fluids from oil wells in order to separate out key components and prepare them for export. Typical oil well production fluids are a mixture of oil, gas and produced water. An oil production plant is distinct from an oil depot, which does not have processing facilities.
In systems involving heat transfer, a condenser is a heat exchanger used to condense a gaseous substance into a liquid state through cooling. In so doing, the latent heat is released by the substance and transferred to the surrounding environment. Condensers are used for efficient heat rejection in many industrial systems. Condensers can be made according to numerous designs, and come in many sizes ranging from rather small (hand-held) to very large. For example, a refrigerator uses a condenser to get rid of heat extracted from the interior of the unit to the outside air.
Marine automobile engines are types of automobile petrol- or diesel engines that have been specifically modified for use in the marine environment. The differences include changes made for the operating in a marine environment, safety, performance, and for regulatory requirements. The act of modifying is called 'marinisation'.
Radiators are heat exchangers used for cooling internal combustion engines, mainly in automobiles but also in piston-engined aircraft, railway locomotives, motorcycles, stationary generating plant or any similar use of such an engine.
In chemical engineering, a jacketed vessel is a container that is designed for controlling temperature of its contents, by using a cooling or heating "jacket" around the vessel through which a cooling or heating fluid is circulated.
Heat exchangers are devices that transfer heat to achieve desired heating or cooling. An important design aspect of heat exchanger technology is the selection of appropriate materials to conduct and transfer heat fast and efficiently.