Heat Exchanger Glossary

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• Baffle Plate  -  Tubes pass through this plate for support.  It provides a blocked path for the shell-side medium, forcing the medium across the tubes for better heat exchanger performance.
• Baffle Spacing  -  The space between baffle plates on a tube bundle.
• Batch Furnace  -  A heat treating furnace where the load enters the quench tank at predetermined times, all at once.
• Bundle Assembly  -  The tube assembly in removable bundle heat exchangers and consists of tubes, tubesheets, baffles, spacers, and tierods.
• Burnout Point  -  At this point in the boiling process, vapor will form to such an extent that it hinders contact between the liquid refrigerant and the heat transfer area, leading to lower heat transfer efficiency.

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• Cavitation  -  The creation and collapse of bubbles in a liquid.  Localized cavities of vapor form on the low pressure side of the pump (suction) and collapse on themselves as energy is added to the fluid.
• Circulation Number  -  In flooded systems, the number of times a specific volume has to pass the evaporator to be fully evaporated.
• Closed Temperature Program  - When the primary and the secondary fluid temperatures are close to each other.
• Compressor  -  A device that forces air or gas into a smaller area increasing the volume and creating a usable force of energy.
• Condenser  -  A device that transfers unwanted heat out of a refrigeration system to a medium (either air, water, or a combination of air and water) that absorbs the heat and transfers it to a disposal point.
• Condenser Coil  -  A series or network of tubes filled with refrigerant, normally located outside the home, which removes heat from the hot, gaseous refrigerant so that the refrigerant becomes liquid again.
• Corrosion  -  The thinning of a pipe wall that is typically caused by a chemical reaction from a corroding fluid or agent and is limited almost exclusively to metal products.  Examples of non metallic corrosion include the dissolution of ceramic materials or the discoloration and weakening of polymers by the sun's ultraviolet light.
• Critical Heat Flux  - At this point, vapor will form to such an extent in the evaporator that it hinders contact between the liquid refrigerant and the heat transfer area, leading to lower heat transfer efficiency.
• Critical Pressure  -  The pressure of substance at the critical point.
• Critical Temperature  -  The temperature of substance at the critical point.

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• Dew Point  -  The temperature at which air must be cooled to become saturated with water vapor.  It is porportional to the amount of water vapor in a given amount of air and when the dew point is raised the more water vapor present, also the opposite.Downstream Pressure  -  The pressure exiting the outlet side of the heat exchanger.
• Dry Bulb Temperature  -  The temperature of air measured by a thermometer shielded from radiation and moisture.

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• End Plate  -  Covers that have been welded to the end of the heat exchamnger.  Most end plates are used on bonnet assemblies.
• Expansion Valve  -  A valve that maintains the pressure difference between the high-pressure and low-pressure sides in a condenser/evaporator system.
• External Pressure Equalixation  -  An expansion valve with external pressure equalization compares the bulb pressure with the suction line pressure in order to control the superheat. Recommended in connection with BPHE evaporators due to the extra V-ring pressure drop.

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• Fin-fan Heat Exchanger  -  A fin-fan is a type of heat exchanger that forces air over a set of coils to cool the process.  It is also referred to as an air cooled heat exchanger.
• Flow Rate  -  The amount of fluid that flows in a given time past a specific point.
• Flue  -  Any vent or passageway that carries the products of combustion from a furnace.
• Fluid  -  A substance that deforms and changes position when put under stress.
• Fluid Dynamics  -  A branch of physics that deals with the effects of force and energy on fluid properties of liquids and gases.
• Fluid Pressure  -  Fluid at rest, exerts a force perpendicular to any surface in comes in contact with.
• Foaming  -  Droplets of refrigerant entering the oil sump, where they are immediately evaporated.
• Forced Circulation System  -  The forced-flow system is similar to a thermosiphon, but the forced-flow system has a pump installed before the evaporator.
• Forward Temperature  -  Temperature of the hot fluid when it enters the device, radiator, or heat exchanger.

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• Gasket  -  A seal between two components, usually bolted.

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• Heat  -  A form of energy that causes physical change in what is being heated.  The lack of heat is cold.
• Heat Capacity  -  The ratio of heat transferred to raise the temperature of an object.
• Heat Gain  -  Heat added to the conditioned space by infiltration, solar radiation, occupant respiration and lighting.
• Heat of Vaporization  -  The amount of heat needed to be consumed to vaporize a specific amount of liquid at a constant temperature.
• Heat Loss  -  The measure of the total heat transfer through your body, clorhing, building walls, etc.  This loss happens in four different ways to transfer heat: conduction, convection, mixing, and radiation.
• Heat Transfer  -  The exertion of power that is created by heat, or the increase in temperature.  It is the transfer of heat from one system to another.  There are four ways to transfer heat: conduction, convection, mixing, and radiation.
• Heat Transfer Coefficient  -  The convective heat transfer between a solid surface and the fluid around it.
• Heat Transfer by Conduction  -  It is the flow of energy between two objects, or within one object, where there is a temperature differential.
• Heat Transfer Rate  -  The amount of hear transfered per unit of time per fluid or material.
• Hydraulic Block  -  A boiler, block consisting of connections to the Brazed Plate Heat Exchanger, instead of pipes, in order to save space. It contains a number of functions, such as threeway valve, bypass valve, fill-up valve and temperature sensors.

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• Inlet Pressure  -  See upstream pressure

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• Lap Joint Flange  -  A flange that consists of two parts, a stub end and the backing flange.
• Latent Heat  -  The energy absorbed or released by a substance during a constant temperature or phase change from a solid to liquid, liquid to gas or vise versa.
• Line Pressure  -  The pressure in the supply line.
• Liquid Hammer  -  In compressors, if a considerable amount of liquid enters the compressor house, a very large pressure can be built up when the piston reaches its top position. This phenomenon is called liquid hammer, and may cause severe damage to the valves or crankshaft.

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• Nipple  -  A short length of pipe either fully threaded (close nipple) or  thread both ends.

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• Oil Separator  -  Separates oil from refrigerant and returns it to the compressor.
• Open Compressor  -  The motor and compressor house are mounted without a shell, although the shaft has a seal.
• Operasting Point  -  In a refrigerant system: the equilibrium point, where the performance of the evaporator matches the performance of the compressor.
• Operating Pressure  -  The operating pressure of equipment occurs when the plant or process is operating at steady state conditions.
• Outlet Pressure  -  See downstream pressure

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• Packed End  -  The end of a heat exchanger which contains the packing joint.
• Pressure  -  It is the force exerted perpendicular to the surface of an object and is expressed as force per unit area.

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• Quad Layout  -  A quadrant type layout.  Four separate quarters of a tube layout with pass lanes between them.

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• Relative Humidity  -  A measure of the amount of moisture in the air with respect to the temperature.

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• Saturated Steam  -  The point (temperature and pressure) when steam is in contact with the liquid water (boiling) it came from.
• Saturated Vapor  -  A vapor at a temperature of the boiling point on the verge of condensing.
• Shell and Tube Heat Exchanger  -  A type of heat exchanger where a process stream is used to heat or cool another process stream.  It consists of two separate, non-moving parts.
• Shell and Tube Heat Exchanger TEMA Designation  -  There are many different types of shell and tube heat exchanger configurations.  To help standardize the types of configurations, the Tubular Exchanger Manufactures Association has devised a standard nomenclature to briefly describe heat exchangers.
• Shell Assembly  -  The assembly into which the tube bundle fits. The shell also contains the shell-side connections.
• Shell Head  -  A formed plate welded to the shell, or bonnet, pipe. It can be many styles or shapes, including flanged and dished, elliptical, ellipsoidal and hemispherical.  Generally, as a head gets flatter, it gets weaker; therefore, designers can use a flat-end plate or a thinner formed head to do the same job.
• Specific Heat  -  The amount of heat required to raise the temperature of a material 1 degree.
• Steam  -  The invisible vapor (gas) when water is heated to its boiling point and passes from a liquid to a gaseous state.
• Steam Density  -  Has a higher density than water vapor, the higher the pressure the higher the steam density.
• Superheated Gas  -  When a dry saturated gas is heated at constant pressure, its temperature rises and it becomes superheated.

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• Temperature  -  The amount of heat or cold, but it is neither heat or cold.  Temperature is expressed as a number that is related to energy and porportional to a type of energy, but it is not energy.
• Tensile Strength  -  The maximum stress a material can resist before it starts to elongate.
• Thermal Conductivity  -  The ability to transfer heat within a material without any motion of the material.
• Thermal Expansion  -  The increase in length, area or volume due to the increase (in some cased decrease) in temperature.
• Thermal Resistance  -  Measures the temperature difference by which an object or material resists a heat flow.
• Thermocouple  -  The junction between two metals generates a voltage that is a function of temperature.  Thermocouples rely on this effect. Almost any metals can be used to make a thermocouple. 
• Thermodynamics  -  A branch of physics and an engineering science that deals with large scale reactions of a system that can be observed and measures and the relationship between properties such as energy, heat, pressure, temperature, work, etc. on a system.
• Tie Rod  -  Bars mounted between the tube sheets to support the baffles.
• Tie Tube  -  A tie tube takes the place of the tie rod in a small diameter heat exchanger, and serves the same purpose.
• Tube Bundle  -  Heat exchangers consist basically of housing and tube bundle.  The housing is a welded construction and includes all connecting, joining and fastening elements.
• Tube Layout  -  Shows the positioning of the tubes inside the heat exchanger and the locations of the tie rods.
• Tube Side  -  The fluid that circulates through the inside of the tubes of the heat exchanger.
• Two-phase Static Head  -  A pressure head created by a liquid/gas mixture.

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• Upstream Pressure  -  The pressure entering the inlet side of the heat exchanger.

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• Viscosity  -  The measure of the internal friction/resistance to the flow of a liquid.
• Volumetric Efficiency  -  The calculation for an internal combustion engine.
• Volumetric Thermal Expansion  -  Takes place in gasses and liquids when a change in temperature, volume or type of substance occures.

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• Water Hammer  -  A valve is suddenly opened or closed.  This can creates a repeating pressure wave of the liquid in the pipe that could cause a rupture to the pipe or even damage equipment.
• Water Hammer Arrester  -  Absorbs unstable pressure due to sudden closing of gate, and moderates the impact of the fluid inside the pipe.
• Weld Neck Flange  -  A flange type that is usually used with pipes, as opposed to pressure vessels.
• Wet Bulb Temperature  -  A temperature that takes into account the relative humidity and the dry bulb temperature.  At any given ambient temperature, less relative humidity results in a greater difference between the dry-bulb and wet-bulb temperatures.
• Wet Steam  -  Wet steam contains both water and steam held in suspension just below the satutation temperature.

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