Heat exchanger superfinishing. Carbon provides the hardness, and the alloying elements provide. Heat exchanger superfinishing

 
 Carbon provides the hardness, and the alloying elements provideHeat exchanger superfinishing  A general procedure [3] that could be used for identifying the most appropriate material for a specific heat exchanger application would consist of the following steps

Radiant tubes are used for natural gas, and are hung vertically to reduce distortion, and to allow the thermal expansion of the radiant tubes. For workpieces used in extreme environments. The heat exchanger is used to heat a cold fluid from 120°F to 310°F. Rather than having a second boiler dedicated to brewing (a dual boiler) or using one boiler for both steaming and brewing (a single boiler), it has a coil attached to the boiler that rapidly heats water as it passes through. A shell and tube heat exchanger is a device where two working fluids exchange heat by thermal contact using tubes housed within a cylindrical shell. · Reduction in lubricant temperature. In this case, the equation above is modified, to replace M m to be the pounds per hour instead of pounds quenched at one time. Exhaust gases from the combustion process are released through the flue to the outside of the home. Consider a heat exchanger where the hot fluid with capacity C h enters at T 1 and leaves at T 2. 5” See pricing and included parts. The differences in friction torque between the flexible and rigid CRBs are compared. A Cu-based Al 2 O 3 ceramic cenosphere porous abrasive ring with phyllotactic pattern was fabricated and assembled into the internal cooling wheel, aiming to the improvement of surface integrity in grinding of superalloy. rates compared with superfinishing. This is the idea behind the form of the heat exchanger design equation: Q ˙ = U 0 A Δ T m. of the tube. 1 Plate-fin heat exchangersThe purpose of a heat exchanger is to transfer heat from one fluid to another, hence the name. A Heat Exchanger is a mechanical device that is used to exchange heat between fluids. Overall Heat Transfer Coefficient. Plate Type Exchangers. Heat exchanger dapat digunakan untuk memanaskan fluida kerja pada suhu yang diperlukan. txt) or read online for free. Accurate and computationally efficient estimation of heat exchanger. At least two matrices are required. Heaters and thermocouples. A heat exchanger is a device built for efficient heat transfer from one fluid to another, whether the fluids are separated by a solid wall so that they never mix, or the fluids are directly contacted. In this short column, we briefly described viscosity and its measurement. The main difference that separates heat exchangers and chillers from each other is their design. Specs: Published by ASM. The price of the unit alone is around $300 to $2,600 depending on the brand. For large diameter, bundles check for U-tube rear support requirements. Pendinginan. Sometimes finned tube heat exchangers, ACHEs, coolers or dryers are enclosed in duct work, and sometimes they are fully exposed with air. With increasing global demands for energy (especially in developing countries), energy production will increase, the wasted energy will increase, and the emission and pollution will increase also. If the part you require isn’t listed below, please contact our sales team on +44 121 359 5401, as a limited number of heat exchangers for certain obsolete British Leyland, Ford, Mercedes Benz and Perkins engines are available. Although different companies and entities may apply their own definition to the term, in. The enthalpy transfer efficiency for an heat recovery unit can be calculated as. A heat exchanger is a system used to transfer heat between two or more fluids. p0260 Grinding is often the simplest and least expensive process for machining hard Noushin Azimy. This. 1. The difficulty of nanoparticle stabilization in the fluids is a significant. The plate-and-frame or gasketed plate heat exchanger essentially. For most continuous furnaces using cold oils, the initial load heats the oil to the operating temperature, and the heat exchangers remove the balance of the heat. If the heat exchanger is located in a hard-to-reach area or requires significant modifications to the existing system, the cost. RAW MATERIAL Bars, tubes or sheets of steel (type 100Cr6 and other) are used as the raw material from which bearing rings are manufactured. 2 kg/s. , hundreds of deaths are caused by cracked heat exchangers and carbon monoxide poisoning. These two integral pathways are usually built out of thermally conductive metals that allow easy heat transfer ( steel, aluminum alloys, etc. This improved surface increases energy/motion transfer efficiency in the metal-to-metal contact area by reducing friction and providing several engineering advantages. Brazed Plate Heat Exchanger. How gasketed plate heat exchangers work. o Define the heat exchanger requirementsA179A179M-90a(2012) Standard Specification for Seamless Cold-Drawn Low-Carbon Steel Heat-Exchanger and Condenser Tubes. This rapid increase in heat can cause the two surfaces to momentarily weld together. One such study by Paul Niskanen et al. 5 times the O. · Optimum surface roughness and stress characteristics. Old age. HEAT TRANSFER FLUIDS. The. 7. To recovery the waste heat from the stripped water, the stripped water will exchange heat with the feed. PDF. 2). Heat exchangers with. H. Motul MT SHIP PROTECT 20L. That being said, there are a few different reasons why your heat exchanger might crack. A very useful concept. 1. Most manufacturers use poor quality bearings that can seize and lead to a complete failure of the gearbox. You will also find examples and applications of heat transfer in various industries and processes, such as heating, cooling, refrigeration. Figure 1. reviewed the impact of isotropic superfinishing on spiral bevel gears using a power circulating pitting (contact) fatigue testing rig. · Reduced contact/surface fatigue. 1 Beyond liquid/liquid. In fact, replacing a furnace heat exchanger can take up to 8 hours and can cost anywhere from $2,000 to $3,500. The use of EHX systems for air conditioning in commercial and industrial settings offers several environmental benefits and is capable of operating in. The heat exchanger is heated by the heat source and warms the air outside. Heat exchangers come in different types that have a. Combustion gases escape through the flue with no system in place to harness the lost energy. The specific mechanisms are usually referred to as convection, thermal radiation, and conduction. 3. Grasas. and Herring, D. Air Cooled Exchangers. Thermal cleaning – Thermally decomposing organic material releasing pyrolysis gasses and leaving behind a coke-like residue – can be up to 100% effective, if the foulant is mostly organic. The average cost of replacing your exchanger is about $1,500. eta =frac { {mathrm {tanh} left (Fa ight) }} {Fa} In the equation above, Fa is the fin analogy number which can be evaluated for some common heat exchanger as what follows. A Review of High Pressure Gas Quenching Technology, Part One: The Heat Transfer Coefficient, HOT TOPICS in Heat Treatment and Metallurgy, Vol. cooling capacity is based on cooling 180° F process water with 85° F water and a 10 psi pressure difference. The cold fluid with capacity C c enters at t 1 and exits at t 2. Water Flashing At The Shell Side Of Heat Exchanger - posted in Industrial Professionals: Attached drawing is a configuration of high pressure steam stripper. Applications: High-temperature adhesive flash and tool masking tape Economical method to hold, insulate. Air cooling system of a heat exchanger has chillers, condensers and fin fans. The furnace heat exchanger is the part of your furnace that heats the air. In the Spotlight: Heat Treat 2023. PDF. The major components of this exchanger are tubes (or tube bundle), shell, inlet head, outlet. In all cleaning processes, operators must use proper protective equipment, such as safety boots, safety gloves and eye protection, to avoid injury. The comparisons between the. The fluids can be liquids or gases, one of which flows inside the tubes while the other flows outside the tubes within. 1. The simplest heat exchanger is one for which the hot and cold fluids move in the same or opposite directions. For this testing, test success is defined as completion of the two hour run with a transmission that is fully functional at the test. , Gear Heat Treatment, Part I & II, Heat Treating Progress, June 2002, July/August 2002. heat exchanger: [noun] a device (such as an automobile radiator) for transferring heat from one fluid to another without allowing them to mix. Carburizing can be performed in the temperature range of 800ºC (1475ºF) to 1090ºC (2000ºF). S. 125 - 500. The units then become BTU/hr for the heat that needs to be removed from the system. The process of heat transmission in. Disebut juga sebagai Fin Fan Heat Exchanger yang memiliki perbedaan cukup banyak jika dibandingkan dengan jenis lainnya. This article focuses on heat exchangers, exploring the various designs and types available and explaining their respective functions and mechanisms. Your heat exchanger supplier can get much. Jenis-jenis Heat Exchanger : 1. Polished Mild Steel Fluid Bed Dryer Heat Exchanger, For Food Process Industry, For Hydraulic and Industrial Process. CSF’s new High-Performance Heat Exchanger for the A90/91 Supra, BMW Z29 Z4 (and other BMW G-Series models). Fig. This makes use of matrix which has high thermal capacity, through which hot and cold fluid pass alternatively. Heat. Concrete Restoration-Grouting (After MEP Installations) a) Concrete surface should be clean, sound and free from oil, grease, cement laitance. 0 or 1. Heat exchangers, as opposed to chiller systems, don’t have a refrigeration unit for cooling their circulating chiller fluid. Heat exchanger. 19 kJ/kg °C. In this new scenario, the plate heat exchanger can play an important role. In another recent study of the optimization of the shell and tube heat exchanger, [2] proposed a method, motivated by constructed theory. The general principles of the mechanical design of the following types of exchangers are given in the Heat Exchanger Design Handbook (1994), and full descriptions of each, are given under the corresponding entries in this encyclopedia: Shell and Tube Exchangers. , he spent two years as a visiting researcher at the National Research Council (NRC) Canada and later served as a Post-doctoral Fellow in the 'Applied Nano. Tribol. This pipe is surrounded by a substance that can be heated, such as cold water. A heat exchanger is a heat transfer device that exchanges heat between two or more process fluids. Hot and cold fluids flow through this porous mass alternately. The design of any heat exchanger is governed by the following equations. Pemanasan. An air pumping device such as an axial flow fan or blower. 3 Superfinishing 10-25 10-3. The fluids are usually separated by a solid wall (with high thermal conductivity) to prevent mixing or they may be in direct contact. Superfinishing the working surfaces of gears and their root fillet regions results in performance benefits. Show more. In the parallel-flow arrangement of Figure 18. So when it is hot outside, your HVAC system and its heat exchanger are responsible for eliminating. Heat treatments optimize the performance and extend the life of gears in service by altering their chemical, metallurgical, and physical. Analysis of thermal performance and ultrasonic wave power variation on heat transfer of heat exchanger in the presence of nanofluid using the artificial neural network. Heat exchangers are required to provide heating and/or cooling to meet a. The water is propelled from a nozzle at an extremely high pressure up to 2500bar (36000psi), blowing away dirt and debris. These two assumptions generally lead to Optimum control of heat exchangers An analysis of the common theory and an example on control development. 1 General. Wait until the system cools before doing anything else to minimize exposure to hot fluids. Specification of tube parameters - size, layout, pitch and material. The process. Heat exchangers are devices that transfer thermal energy from one fluid to another without mixing the two fluids. The Importance of Isotropic Superfinishing. Air Cooled Heat Exchanger. Heat exchangers are crucial in thermal science and engineering because of their essential role across the landscape of technology, from geothermal and fossil power generation to refrigeration,. So, the heat transfer between the flowing fluid in these channels is very high. 289. A previous article presented guidelines for cost-effective recommendations. The entire heat transfer process takes place in the large tube. liquid to liquid. Tube Tech guarantees to remove 90%+ fouling from the shell and tube side of heat exchangers. Choose from our. An abrasive phyllotaxy arrangement internal cooling grinding wheel that is a combination of an ICGW and abrasive phyllotaxy arrangement was proposed in. 1) Determine that the exchanger is operating correctly as designed. A properly designed heat exchanger can be used for both heating & cooling operations. 10-3. Key benefits of the isotropic surface finishing process. Heat exchangers are used in both cooling and heating processes. The heat exchanger is sized (plus safety margin) to remove the heat of the weight per hour. iii. 500L View Details. Shell-and-Tube Heat Exchanger. Contoh penggunaan heat exchanger pada pemanasan adalah pada industri petrokimia dan pembangkit listrik. On the other hand, the lubrication prevents the heat development between the two moving surfaces. In a liquid cooling loop, the coolant is pumped through a cold plate that is in contact with a heated. Introduction. Teaching Assistant: • Technical Drawing Ⅰ. Cutting draw technology. The Alfa Laval HEXpert selector tool makes it quicker than ever to find your ideal heat exchanger. Some simple examples of shell and tube heat exchangers include boilers, which heat. Category: Science & Tech. Non-condensing units are fitted with just the 1 heat exchanger, whereas modern condensing. · Reduced contact/surface fatigue. This is the idea behind the form of the heat exchanger design equation: Q ˙ = U 0 A Δ T m. As with the primary heat exchanger, the secondary exchanger will probably have a fairly long warranty period. Most heat exchangers come with a 10-to 20-year warranty, which usually only covers. Heat exchangers play a critical role in supercritical CO 2 Brayton cycles by providing necessary waste heat recovery. Carbon provides the hardness, and the alloying elements provide. Disebut juga sebagai Fin Fan Heat Exchanger yang memiliki perbedaan cukup banyak jika dibandingkan dengan jenis lainnya. 2. CAPACITY ADJUSTMENT. 4 Methodology of Heat Exchanger Performance Assessment 4. The water is considered as hot fluid flowing in the tube, whereas air is cooling fluid in encloser volume or duct area. Heat exchangers use one of four basic flow designs: “(i) Cocurrent flow, (ii) Countercurrent flow, (iii) Crossflow, (iv) Hybrid flow”. The company's product portfolio includes Nuclear Power Plant Heat Exchangers, Air-Motor Coolers, Turbine Oil Coolers, Transformer Oil Coolers and Gas Coolers. Recommended for long-term protection of metal parts, for storage or shipping. Air Coolers, Chillers, and Condensers. Untuk heat exchanger ini sendiri akan menggunakan bantuan mekanik dalam penurunan dari suhu fluidanya itu sendiri. Suitable for fluid. Heat exchanger ini terdiri dari plate / lempengan yang ditumpuk berlapis - lapis. Fouling is a challenging, longstanding, and costly problem affecting a variety of heat transfer applications in industry. This high performance also allows the specification of very approach temperature (as low as 2 to 5oF) which isThe heat exchanger is an integral part of a furnace. Motul MT SHIP PROTECT 20L. 3. During his Ph. Fluidos de transmisión. The traditional standard type of heat exchanger is the shell and tube,. NUMBER OF PAGES . A plate heat exchanger is used to transfer heat energy from one fluid to another. Steve Hansen, that's me, the Senior Editor of Costimates. A very useful concept that goes along with total resistances is the overall heat transfer coefficient. 20 minutes with C. A plate heat exchanger is a type of heat exchanger that uses a series of metal plates to move heat from one fluid to another. The basic pieces and parts in a chiller (both air-cooled and water-cooled) are rather similar. Also, over time, this will easily cause the heat exchanger to crack. number of shells in parallel/series, temperature control scheme, etc. LIMITATION OF ABSTRACT . The various aspects of isotropic superfinishing and isotropic superfinishes that have been. . ( Learn more about myself and our team) I'm an avid home improvement professional with more. The most important advantage of these printed circuit heat exchangers is the very high heat transfer coefficients. Download as PDF. HomeAdvisor: $1,000 - $2,000, Heat exchanger replacement. Selection of heat exchanger TEMA layout and number of passes. By utilizing non-abrasive, high-density media in conjunction with an isotropic superfinishing (ISF) chemistry, surfaces can be superfinished to an isotropic or random finish. A zero surface area represents a system without a liquid-suction heat exchanger whereas a system having an infinite heat exchanger area corresponds to an effectiveness of unity. These values, typically 800 to 1200 Btu/-hr·ft2 oF (clean), result in very compact equipment. This added cost will likely be negated by heat savings, as heating moist air requires a lot more energy than heating dry air. · Prevents micro and. You will also find examples and applications of heat transfer in various industries and processes,. Reflecting modern developments in the science and practice of modern grinding processes, the Handbook of Machining with Grinding Wheels presents a Manufacturing - Beno Benhabib 2003-07-03The SUPERCHANGER® Plate And Frame Heat Exchanger, sometimes referred to as a gasketed plate heat exchanger or GPHE, provides outstanding efficiency transferring heat from one liquid to another, often water to water, or from steam to liquid. Āvāz, Khuzestan, Iran. A shell and tube heat exchanger is a device where two working fluids exchange heat by thermal contact using tubes housed within a cylindrical shell. Many scholars are also committed to studying its heat transfer. In practice, all the thermal duty of the hot fluid (fc) is transferred to the cold fluid (ff), thereby fulfilling the next energy balance: The thermal duty of a fluid in liquid state depends on the mass flowrate and the temperature differential. Expectations for a chemically accelerated superfinishing process. c p for water = 4. turning, heat treatment, grinding and assembly. Pendinginan. Motul RUBRIC HM 46 208L. The cost of installing one will usually be $400 to $600. Superfinishing is also better suited at sealing workpieces than other finishing processes. STANDARDS: • DENISON HF-0 • ISO 11158 categories HM ; ISO 6743-4 categories HM • DIN 51524 part 2, HLP • NF E 48603 H. The most common application of heat transfer is in designing of heat transfer equipment for exchanging heat from one fluid to another fluid. 2. 4% on the. This introductory text is intended for use in a first course in heat transfer for undergraduate engineering students, and as a reference book for practicing engineers. 8(a) , the hot and cold fluids enter at the same end, flow in the same direction, and leave at the same end. The tests indicated that superfinishing offered no improvement in performance due to the high lubricant film thickness generated by the extremely high. This is achieved by removing just the thin amorphous surface layer left by the last process with an abrasive stone or tape; this layer is usually about 1 μm in magnitude. 1 through 4 show an embodiment of the invention applied to a superfinishing machine for superfinishing the outer peripheral surfaces of annular workpieces, wherein FIG. Endothermic atmospheres are commonly used during the heat treatment of steel. 1. Vacmul EDM 3 is a highly refined, narrow-cut, low viscosity fluid specially suited to finishing operations where a high quality finish is required. However, it can cost as little as $500 or as much as $3,500. For this reason, Arrow has added the capability of Isotropic Superfinishing. 005”-0. Our shell and tube heat exchangers are used in many comfort and industry applications for heating and cooling fluids. D. The furnace then brings in cool air from your home using the air return ducts. Critical elements: Heat exchangers at an oil refinery. The media may be separated by a solid wall to prevent mixing or may be in direct contact. Due to. 2. h 1 = enthalpy in outside make-up air before the heat exchanger (kJ/kg, Btu/lb) h 2 = enthalpy in outside make-up air after the heat exchanger (kJ/kg , Btu/lb )Published on August 18, 2022. Utilizes metal plates to transfer heat between two fluids. Section snippets Numerical modeling and analysis. Otto, F. Heat exchangers may be divided into several categories or classifications. Upgrade your gearkit with REM superfinishing to give a much smoother surface finish to the gears. A hot, less-dense lower boundary layer sends plumes of hot material upwards, and cold material from the top moves downwards. The company was established in 1947, and ten years later, it created the brand Basco, which specializes in. Heat exchanger juga dapat digunakan untuk mendinginkan fluida kerja pada suhu yang diperlukan. As its name implies, this type of heat exchanger consists of a shell (a large pressure vessel) with a bundle of tubes. Open the catalog to page 1. The unit. Additionally, this article outlines the selection considerations and. 1 ratio has been used with certain applications using a 3. In this case, the total heat transfer rate is evaluated through a concept of total surface effectiveness or surface efficiency η o defined as: (1) where A f is the fin surface area, A p is the primary surface area and A = A f + A p. Copper remains the preferred covering in continuous inkers due to its low ink and high heat. Channel and shell cylinders are typically rolled and welded plates (greater than 24-inch diameter) or pipe (24-inch or less diameter). Date stamps and inserts Quick connectors and nipples Pressure plugs Sintered vents Heat transfer pipes. 4. 1. Image Credit: Anton Moskvitin/Shutterstock. Combining Eqs. The fluids can be separated or in direct contact according to the type of. Abstract. However, most homeowners pay around $1,750. Request a quote today. from 0. Most companies suggest a complete exchange. Just answer a few short questions and get a customized recommendation to meet your unique needs. Superfinishing,. Baffles are used on the shell side to increase turbulence, prevent stagnation and improve the heat transfer rate. The cracks break the seal from the combustion chamber and let soot come through to the other side. A furnace’s heat exchanger is a set of tubes or coils looped repeatedly through the airflow inside your furnace for heating air. C. Popular in Industrial Heat Exchanger. The effectiveness is the ratio of the actual to maximum possible heat transfer rates. The wrong material can lead to higher cost and longer production times if it’s more difficult to. Correcting flaws in construction and piping that may have a detrimental effect on heat transfer and pressure drop may be the solution. Radiators and Solar Exchangers. Reduce Downtime and Maximize Profitability with Tube Tech’s Heat Exchanger Cleaning Service. Pemanasan. However, in heat exchanger applications with corrosive fluids only corrosion-resistant metals, e. Flat Plate and Fin Exchangers. Heat transfer, any or all of several kinds of phenomena, considered as mechanisms, that convey energy and entropy from one location to another. Check the requirement of Heat Treatment for the inner two rows for C. Poorly installed systems can result in problems ranging from the minor to the catastrophic. Another approach introduce the definition of heat exchanger effectiveness (Є), which is a dimensionless with ranging. The double pipe heat exchanger has a small pipe that is surrounded by another large pipe. Know more . A general procedure [3] that could be used for identifying the most appropriate material for a specific heat exchanger application would consist of the following steps. 3 Duties other than turbulent liquid flow 32. Complexity: The complexity of the installation can also affect the cost of replacement. Recommended for long-term protection of metal parts, for storage or shipping. range of bespoke engine heat exchangers. MSDS Data sheet difficult conditions of metals parts and assemblies. In this method, a global heat exchanger is divided into several sub heat exchangers in series-and-parallel arrangement [14]. 1 No. 2. STANDARDS: • ISO TR 3498: L-FD and L-HM • ISO. Heat exchangers are used in many engineering applications, such as refrigeration, heating and airconditioning systems, power plants, chemical processing systems, food processing systems, automobile. The plate heat exchanger (PHE) is a specialized design well suited to transferring heat between medium- and low-pressure fluids. Heat Exchangers. Its application to superfinishing process required the information about how the abrasive cutting edges and their protrusion heights are distributed at and near the stone surface,. Also, we can use these systems in a very wide range of temperature applications. Maximum uptime - less fouling, stress, wear and corrosion. 4. A heat exchanger is a system used to transfer heat between a source and a working fluid. In cases of combined heat transfer for a heat exchanger, there are two values for h. In a recent evaluation, a major bearing manufacturer monitored the performance features of two, functional metal-to-metal contact surfaces using an ASTM D 2714. pdf), Text File (. Heat exchanger prices depend on several factors, quality, size, energy efficiency, and whether it is a gas or electric furnace. Condenser is used for cooling the object till the changing of phase from gaseous to liquid. Show more. They consist of a shell with traditional plain tubes or enhanced surface tubes for high thermal performance. To meet these needs, it is necessary to expand the knowledge of heat-treating and quenching to consistently produce a quality product, capable of being manufactured in a cost-effective manner. High pressure cleaning can reduce safety. Gears enable motion through power transfer in key sectors, including automotive, aerospace, marine, off-highway, and industrial applications. The heat treatments were applied in a two chamber Ipsen RVTC furnace in vacuum atmosphere. Asperities on these surfaces introduce friction (inefficiency) into the mechanical transfer of energy, resulting in energy loss which can most noticeably be monitored as heat generation. The second in a two-part series, this installment addresses induction gear hardening by encircling the whole gear or sprocket with an induction coil, also known as ‘spin hardening. Our engineered technologies allow us to tackle any substance or severity of fouling. One of the oldest ways to check for heat exchanger cracks is to simply observe the flame when the blower starts. If water collects at the base of your furnace, or there’s excesses soot or strong smells coming from your furnace, it’s most likely cracked. PROEDM 4. EXPRESS-GLANZ 12X0. Plate Fin. 25 micro inches on the Ra scale. Choose from our selection of heat exchangers, including over 350 products in a wide range of styles and sizes. • Fluid Mechanics. Heat Treatment of Gears is designed to provide the gear design engineer with a better understanding of heat treatment and its effects on gear quality and performance, especially as these considerations are critical to ensuring that the gears perform satisfactorily under anticipated service conditions. The primary heat exchanger is the one closest to the burner in the furnace. The heat transfer condition in HEDG is much different from that in conventional grinding, it can be analyzed by a new thermal model of circular arc contact surface. Mark R Riggs. 19a. The heat exchanger then transfers the heat from the furnace to the outside air. Heat Transfer: Introduction to three types of heat transfer, Conductive heat transfer, Fourier’s law of heat conduction, Thermal conductivity of materials, Differential equation for heat conduction in rectangular,. The fluid temperature inside the shell and tube are different and this temperature difference is the driving force for temperature exchange. For now, let’s focus on U 0 A and delay our discussion of the temperature driving force, Δ T m, until a bit later. 7. Double Pipe or Hairpin Exchanger Design. qT = UAΔT1 − ΔT2 lnΔT1 ΔT2 = UAΔTlmtd, where ΔTlmtd is the log-mean temperature difference. Processes Honing Figure 2. This will help you to prepare the heat exchanger specification.