Heat exchangers are an equipment targeted to the efficient transfer of heat from a hot fluid flow to a cold fluid flow, in most cases through an intermediate metallic wall and without moving parts. We here focus on the thermal analysis of heat exchangers, but proper design and use requires additional fluid-dynamic analysis (for each fluid flow), mechanical analysis (for closure and resistance), materials compatibility, and so on.

Heat losses or gains of a whole heat exchanger with the environment can be neglected in comparison with the heat flow between both fluid flows; i.e. a heat exchanger can be assumed globally adiabatic. Thermal inertia of a heat exchanger is often negligible too (except in special cases when a massive porous solid is used as intermediate medium), and steady state can be assumed, reducing the generic energy balance to:

where the total enthalpy h_t has been approximated by enthalpy (i.e. negligible mechanical energy against thermal energy), and D means output minus input.

Although heat flows from hot fluid to cold fluid by thermal conduction through the separating wall (except in direct-contact types), heat exchangers are basically heat convection equipment, since it is the convective transfer what governs its performance. Convection within a heat exchanger is always forced, and may be with or without phase change of one or both fluids. When one just relies in natural convection to the environment, like in the space-heating hot-water home radiator, or the domestic fridge back-radiator, they are termed ‘radiators’ (in spite of convection being dominant), and not heat exchangers. When a fan is used to force the flow of ambient air (or when natural or artificial wind applies, like for car radiator) the name heat exchanger is often reserved for the case where the ambient fluid is ducted. Other names are used for special cases, like ‘condenser’ for the case when one fluid flow changes from vapour to liquid, ‘vaporiser’ (or evaporator, or boiler) when a fluid changes from liquid to vapour, or the ‘cooling tower’ dealt with below. Devices with just one fluid flow (like a solar collector, a spacecraft radiator, a submerged electrical heater, or a simple pipe with heat exchange with the environment) are never named heat exchangers.

To be continued…

Image credited to heatexchangerguy.com/plate-heat-exchangers.html

Brief information about the company: Sunny Steel Enterprise Ltd. is a professional steel exporter in China, specializing in the production of steel product, including stainless steel, galvanized steel, pre-painted steel and carbon steel sheet, ceramic lined composite steel pipe and fittings, elbow, plate, coil and the related products, covering pipe & tube , fitting, bar and wire rod etc. Based on the standing better and faster service?they have been the best partner both of the steel factories and suppliers. The company offers perfect service to the mills and bring in the highest quality levels at the most competitive price for our customers. Their entire operations are focused on the precise demands of our customers needs.

Chairman and Chief Executive Officer Guohong Zhao commented, “We continued to build on the positive momentum generated in recent quarters and ended 2010 with a very solid performance. Top-line growth, which exceeded our guidance in the fourth quarter, contributed to more than 44% increase in revenues for the full year. At the same time, our focus on optimizing both our product mix and cost structure allowed us to almost double our net income in 2010.”

“Our diverse product lines enable us to cater to a broad range of customers and end users as we capitalize on several key trends that are driving the clean technology movement in China. As China faces pressures from rapid urbanization, our heat exchanger units offer efficient and effective solutions to provide heating systems to growing populations in cities throughout China. In addition, our air-cooled exchangers enable water-deficient areas in Northern China to conserve and better utilize a very limited resource. As businesses recognize the cost effectiveness of switching to clean technology solutions and are further incentivized by government stimulus plans, our plate heat exchange (“PHE”) products are quickly gaining traction across a range of industrial sectors, including the metallurgy, petrochemical and shipbuilding industries.

“As rapid urbanization and government stimulus plans designed to support carbon reduction initiatives continue to drive demand for energy efficient platforms, our broad product portfolio, integrated solutions and excellent track record of high quality applications have well prepared us to capitalize on these favorable dynamics in 2011. Additionally, our sound balance sheet and cash position, which were further strengthened by our recent fund raising, afford us with financial flexibility to invest in our future and pursue growth opportunities.”

Please read the rest of the news here.

If you are in this industry, you will definitely know how expansive a heat exchanger can be. Unless you can fabricate your own heat exchanger, that will save your company substantially a lot. Unfortunately, many companies have to purchase it from heat exchanger manufacturer. But, one good thing took place recently. DENSO Corporation has just developed 4 units of low cost heat exchanger to support the Indian automotive market. Continue reading the news below:

Kariya (Japan) As part of its ongoing effort to develop low-cost products for emerging markets, DENSO Corporation has developed four heat exchangers for the Indian market. DENSO’s new radiator, heater core, condenser and evaporator use common, locally sourced materials and are manufactured on a single production line, which helps to significantly reduce cost.

“While maintaining our DENSO quality, we’ve succeeded in substantially lowering the cost of these products by increasing our local procurement, and by using common materials to reduce the types of materials we use by more than 70 percent,” said Akio Shikamura, senior executive director of DENSO’s Thermal Systems Business Group. “We will share the newly developed cost-reduction techniques throughout the company to improve the competitiveness of our products worldwide.”

When developing the new products, DENSO carefully assessed the needs of the Indian market to determine optimal specifications, while also using India’s locally made and widely available materials. This increased local procurement, and increased the number of common materials and components for each product.

Continue reading here.

Now, there’s the old and traditional furnace type of a home heater. Such a type of heater have been used way, way back before you may even been born. Basically the furnace works by receiving air through a series of pipes and exhausts. The air that has been taken to an area where it’s being warmed is then circulated towards a blower for filtration, and most often, furnaces is powered by electric and can be powered by gas as well. Such type of heater can also be modified to use coal, oil and the usual… wood. However, if you opt to choose such a type of residential heat exchanger, make sure that you check the variable speed fan of the model. The speed of its fan will have a great deal in energy usage depending on its size which is quite advantageous more than the conventional units.

Heat pumps are likewise good as home heaters; however there are two kinds of heat pumps that you have to consider. The air source heat pump which use warm exterior air as its source of heat, then gives added heat if necessary. However such kind of heat pump is only appropriate in warm places, you are going to need an air-conditioning unit to be attached into its main set up, using the same process in cooling the air.

Ground source on the other hand which is the second type of a heat pump, otherwise known as geothermal heat pumps uses underground heat. Which such heat basically stays constant the whole year through, which can be taken right underneath your home. It’s not really as popular as the former, but the latter as some installers have insinuated saves greater energy and can be used as water heater as well due it has a larger price attached to it.

These are just some of the few residential heat exchangers that might be beneficial and useful for you, if you need some more information of such type of other residential heaters. Visit us at http://www.aabbottferraro.com and learn more about the different kinds of heat exchangers as well.

Hairpin heat exchanger is available in several components; it is available in single-tube or double pipe or multiple tubes in a hairpin shell, finned tubes, straight tubes, fixed tube sheets and removable bundle as well as bare tubes.

Hairpin bare, double-pipe and multi tube were made using U shape pipes which are connected to two tube sheets and are loaded within a hairpin shaped shell. There are several advantages in using such units:

• U shape bundle is free for extension and reduction within the hairpin shell ridding the need for extending its joint.

• The tube bundle is detachable which makes its cleaning easy and possible on the side of the shell.

• Bare Multi-Tube and Double-Pipe Exchangers offer the least pressure drop among most exchangers.

• These units are able to carry the maximum pressure permitted by the ASME Code for every thickness of the used wall. Higher pressures are promising by using higher stress value materials.

• For procedures that needs regular technical and mechanical cleaning and maintenance, bare tube offers easiness of maintenance and convenience.

• Double-pipe heat exchangers and bare multi-tube exchangers offer the smallest amount of pressure drop amongother heat exchangers in the industry.

• Often times the procedure might be customized or totally modified, the flow rate of the stream or other situation might likewise vary. The Double Pipe Hairpin is basically created to adjust to these modifications simply by reorganizing the sectors. Limitless figures of sectors could be set in correspondence and sequences to fit the procedure conditions that are essential to its new requirements.
However, there’s a certain limitation in these units, only the chemical tube side of the heat exchanger can be cleaned.

The Multi-tube and Finned Double pipe have certain advantages as well:

• It has the same advantages as of the bare tube hairpin heat exchanger

• Finned Double pipe generally have four times heat transfer surface than bare tube heat exchanger. It is an advantage especially if the shell side heat transfer coefficient is less thus it requires more surface.

• Better application for high shell side thickness with minimal heat transfer coefficient, finned hairpin heat exchanger is a good application in cooling sticky and thick liquids. The thickness of the fin wall would be higher than an regular mass thickness, which makes the fin yields a lesser film coefficient, reducing the transfer of heat and causes extreme stinking.

However, its cleaning is limited to the tubes finned surface alone. For more information on the hairpin heat exchanger, visit http://www.hed-inc.com

Heat exchangers are the very responsible for such amenities. They may come in huge and bulky shape but there are those can easily fit and were custom made to fit in our homes.

There is even a solar powered water heating systems that has been developed for residential use, marking the ever growing knowledge of human in use and be applied to our living condition today.

There are two types of heat exchangers, the liquid-liquid heat exchanger and the air- liquid heat exchanger. However it’s the liquid-liquid heat exchanger that have been classified into two kinds, which is the single wall and the double wall heat exchanger.

The double wall heat exchanger has two walls between the two liquids inside the heater; it is often used to prevent the poisonous element such as antifreeze liquid also known as ethylene glycol in entering into the potable water. Double wall heat exchangers therefore are required as a safety measure in case leaking may occur; making sure that the ethylene glycol solution will not contaminate the filtered water supply.

However, one of the known disadvantages that have been noticed in double wall heat exchanger is that no matter how efficient its safety measure is. It is still reduced due to the transfer of heat through the two surfaces. It is therefore essential that such heat exchanger should be twice the size and much bigger than the single walled heat exchanger. Basing on the simple principle, to be able to transport same quantity of heat, the double wall heat exchanger should be bigger than the single wall heat exchanger.

On the other hand, the air-liquid kind of heat exchanger doesn’t need a heat exchanger from solar collector to its distribution system.

For more information on such types of heat exchangers visit http://www1.eere.energy.gov and learn as well as find the most effective and useful type of heat exchanger for you. Living in an advance and modern technology have its pros and cons however, it would more advantageous for us if we know what to do and have the necessary information on how to use such machines and devices.

Pipes are used in heat exchangers to heat or cool one fluid by transferring heat between it and another fluid. Often the exchanger consists of a coiled pipe containing a fluid that passes through a chamber containing another fluid. The walls of the pipe are usually made from metal (used for its high thermal conductivity) to facilitate the interchange. The outer casing of the large chamber is made of a plastic to prevent the heat from escaping from the exchanger.

Plate heat exchangers (otherwise known as PHE) were invented in 1923 by Dr. Richard Seligman and revolutionized the then methods of indirect heating and cooling of fluids.

There are many advantages to the plate heat exchanger, such as compactness, the units in a plate heat exchanger occupy less floor space.

Flexibility is another advantage, as many changes can be made to heat exchanger performance, such as modifying design specifications, conditions and fluids.

Plate heat exchangers are made from pressed plates, allowing greater resistance to corrosion and chemical reactions, they also have the added advantage of being cheaper than their alterative, welded plates.

The article can be easily dismantled for inspection and cleaning and the plates are replaced easily and individually, saving on cost. It also operates with small temperature differences, this is a benefit when high temperatures must be avoided.

There are also some disadvantages to using this type of heat exchanger, such as a potential for leakage.

Many a cooling tower company produces plate heat exchangers as part of their production.

This article is adopted from: http://education.ezinemark.com/plate-heat-exchangers-169a3d39030.html

Shell and tube heat exchangers are special type of unit operation which is needed for high-pressure applications; they are durable products, which can withstand the demands of many working environments. Their design plays a large part in ashell and tube exchanger’s ability to endure exceedingly-challenging situations. The gaskets are normally spiral wound gaskets made of stainless steel.

Shell and tube heat exchangers are made from a series of tubes, which can be made of durable material such as fluoropolymers. Fluoropolymers are highly-durable plastics such as PTFE, FEP, and PFA. Fluoropolymers, like heat exchangers, have a place in a variety of industries such as the automotive, medical, and aeronautical.

In a heat exchanger’s shell, one set of tubes contains fluid, which is either heated or cooled. Another set of tubes also contains liquid, which facilitates the heating or cooling of the primary set of tubes. A tube set is referred to as the tube bundle and can take on a variety of shapes depending on what is most conducive for the intended job.

Engineers of shell and tube heat exchangers need to consider several components of construction, among them are:

• A smaller tube diameter enables the shell and tube exchanger to be economical and compact, yet a tiny diameter can facilitate malfunction and difficulty of cleaning. Larger tubing can be instituted to eradicate potential flow and cleaning problems. Engineers must factor cost, space, and the propensity of liquids to foul when constructing a heat exchanger.
• Tube thickness is important to make sure there is room for corrosion; vibration existing in the product has resistance; and, the shell and tube exchanger can withstand pressure coming from both in and outside of its internal tubes.
• Folding or wrinkling the inner tubes increases the flow of the liquid, which facilitates the transfer of heat, producing better performance from the exchanger.
• Designers also consider the layout of the inner tubes. Tubes can be fashioned in a triangular, square, rotated square, or rotated triangular fashion. Particular, internal designs are conducive to specific jobs and the elimination of potential problems such as fouling of the liquid.
• Shell and tube heat exchangers also host baffle components. Baffles serve several purposes such as holding the tube bundles in place; making sure tubes do not sag or vibrate; and, facilitating fluid flow.