One Stop Heat Exchanger Information

A ‘heat exchanger’ may be defined as equipment that transfers the energy from a hot fluid to a cold fluid. Here, the process of heating or cooling occurs. In heat exchangers the temperature of each fluid changes as it passes through the exchangers.

Examples of heat exchangers
• Intercoolers and heaters
• Regenerators; refrigeration units
• Automobile radiators
• Milk chiller of a pasteurizing plant
• Condensers and boilers in steam plant
• Evaporators
• Oil coolers of heat engine

Applications:
• Environmental Engineering
• Waste Recovery
• Manufacturing Industry
• Air – conditioning and Refrigeration
• Process chemical food industries
• Electronics
• Power Production

CLASSIFICATION
Heat exchangers may be classified according to the following main criteria:

1. Nature of heat exchanger process
2. Flow arrangement
3. Physical state of fluids
4. Geometry and construction

1. Classification based on Nature of heat exchanger process

(i) Direct contact:
Heat transfer will occurs by direct mixing of two fluids. This is preferred when the direct mixing is harmless or desirable.
Ex: cooling towers
(ii) Indirect contact:
Heat transfer will occurs through a separating wall between two fluids
Ex: Regenerators and Recuperators

2. Classification based on Flow arrangement

According to the relative directions of two fluid streams the heat exchangers are classified into the following three categories:
(i) Parallel flow or co-current flow heat exchangers
(ii) Counter-flow heat exchangers
(iii) Cross-flow heat exchangers

(i) In a parallel or co-current flow heat exchanger
As the name suggests, the two fluid streams (hot and cold) travel in the same direction. The two streams enter at one end and leave at the other end. The flow arrangement and variation of temperatures of the fluid streams in case of parallel flow heat exchangers, are shown in the below figure. It is evident from the figure that the temperature difference between the hot and cold fluids goes on decreasing from inlet to outlet.
In parallel flow, it is not possible to bring the outlet temperature of the cold fluid nearly to the inlet temperature of the hot fluid. This type of heat exchanger needs a large heat transfer area, so, it is rarely used in practice.
It is particularly useful when sudden cooling or sudden heating is required.
Examples: Oil coolers, oil heaters, water heaters etc.

(II) Counter-flow heat exchangers
In a counter-flow heat exchanger, the two fluids flow in opposite direction. The hot and cold fluids enter at the opposite ends. The flow arrangement and temperature distribution for such a heat exchanger are shown schematically in the below figure.
In this flow, it is possible to bring the outlet temperature of the cold fluid nearly to the inlet temperature of the hot fluid. This type of heat exchanger needs a small heat transfer area, so, it is widely used in practice.
Examples: Oil coolers, oil heaters, water heaters etc.

(iii) Cross-flow heat exchangers
In cross-flow heat exchangers, the two fluids (hot and cold) cross one another in space, usually at right angles. The flow arrangement and temperature distribution for such a heat exchanger are shown schematically in the below figure.

Source: enggyd.blogspot.com/2010/03/description-of-heat-exchange-equipment.html

The Sandia mini-reactor would be about the size of a two- or three-storey office building. At its heart is a small uranium core submerged in a tank of liquid sodium. The sodium capturies the high temperatures of the core and carries it to a heat exchanger, where liquid carbon dioxide then absorbs the heat. The CO2 expands rapidly, forcing its way through a jet-like turbine that spins an electric generator. It would be a closed-loop system, meaning the CO2 would be recycled over and over again.

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Tube Tech International proved that previous industry standards for cleaning such equipment with U bends were inadequate and, for the first time on this unit, Tube Tech gave not only the straight legs, but also the U sections a complete internal clean.

Who says O&M instructions have to be in print? Combining real-life footage with animation, this video offers clear instructions in 10 segments. Direct mailed to customers for added value.

A heat exchanger is an equipment or device built for efficient heat transfer from one medium to another, whether the media are separated by a solid wall so that they never mix, or the media are in direct contact. Heat exchanger are widely used in refrigeration, space heating, air conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, and natural gas processing. A common example of a heat exchanger is the radiator in a car, in which the heat source, being a hot engine-cooling fluid, water, transfers heat to air flowing through the radiator.

In industry, specifically process or manufacturing plants there are other types of heat exchanger such as plate heat exchangers, spiral heat exchangers and shell and tube heat exchangers. All of these heat exchangers are special and have their dedicated purpose or function when being employed. The price, size, specification, purpose and design varies within each other.

Heat exchanger must be properly maintained in order for it to be working efficiently and effectively. Energy is being transferred from one side to the other, thus it acts like an energy saver. When the heat exchanger is no longer efficiently transferring heat, it is time for cleaning. Hence, the heat exchanger will be stopped and cleaned from scale sticking on the surface of the wall. Failing to clean the heat exchanger will result to tremendous lost of energy.

Heat exchangers tubes are part of the heat exchangers, which is used to efficiently transfer heat from one medium to another without mixing the fluids physically. The device has a range of applications such as space heating, cooling, power, air conditioning, petrochemical factories, chemical factories, refineries and processing of natural gas.

A typical example of this instrument is located in cars, more familiarly known as radiator, where it works as a means to transfer heat from the water of the engine, to the air through the generator. There are several types of radiators and each is crafted to suit the application where each is used.

After certain period of time of heat exchanger operation, it will be inefficient. Hence, a better way to increase the capacity of working with the heat exchanger tubes is a complete cleaning. There are a number of advantages of cleaning the heat exchanger. The first reason is to protect the system of sudden and unexpected errors. Apart from this, they will also function properly and the cleaning will also improve the efficiency of the device. Check the heat exchanger tubes at least once every three months to lengthen the life of your heat exchanger and will make you have every penny’s worth of your investment.

Since the cleaning of heat exchanger tubes is beneficial, how does one do it? What are the procedures for cleaning? Here are some points to consider:

* Pull the heat exchanger unit from any electrical devices. This is followed by removal of loose materials found close. This will prevent possible pushing of these materials towards the tube’s interior once you start brushing.

* The next thing to do is remove the material inside the tube before you use the appropriate size of the brush to clean. Nylon brush cleaning process each sound within the pipe and the removal of existing materials or furniture inside.

* Sometimes the cleaning of the interior is not enough for you by just scraping the internal walls to remove the materials of the tube. It is important that you scratch using materials that are less strong than the materials from the heat exchanger materials to avoid damaging the tubes.

* After all the above step, let the water rush through the inside, to remove other materials not perfectly taken out by scraping. It will also lighten up the interiors.

Stephan Bevan writes for the Toronto Plumbing contrator: Draincom.com. If you need a water heater repair or installation please give us a call at: 416-989-5757.

One type of heating system that is starting to gain popularity in home construction, is the installation of geothermal heat pumps (also called GeoExchange, earth-coupled, ground source or water-source heat pump). Basically this system replaces all fuel-fed furnaces and air conditioners by having a pump buried deep in the ground. The pump circulates hot and cold air from a series of pipes that are installed in the ground outside the house. The air is circulated into the house using a series of fans and vents through ductwork which comes from a ground heat exchanger into the home. The operating savings can be substantial as no fuel is necessary to heat or cool your home. For more reading information on geothermal heat pumps, please refer to wikipedia.

I will be listing all websites, blogs, forums etc that is related to Heat Exchangers. If you happen to know interesting and informative heat exchanger sites, please feel free to let me know (by contacting me via the contact form). If you have your own heat exchanger site, feel free to provide me relevant details so I can list it here. Cheers.

Installation of Plate Heat Exchanger
Heat Exchanger World
Heat Exchanger Cleaning

Updates shall be carried out from time to time.

By: JEANNIE GRIMWOOD

There are different home-heating systems that can save you more money on fuel costs. Those of you that are using wood stoves can get even better use of your burn time by the following methods.

Before every heating season, have chimney stacks adequately cleaned to aid drafting and prevent stack fires. Green and unseasoned wood causes greater creosote buildup, which results in other problems. It reduces combustion and increases the hazard of a fire.  Layers of soot inside the stove reduce heat transfer to your home. Cleaning out the inside of your wood stove improves heat transfer. Chimney brushing can take from 20 minutes to several hours depending on stack length and complexity.

Install a “wetback” or water-jacket system to your wood stove. Heating household water through your woodstove is a good money saver. Some stoves come with accessories to attach water pipes. Installation time depends on distance between the stove and hot water heater.

Fuel-efficient heating systems are another way to save. Small forced air space heaters such as Monitors are excellent for smaller homes. They use minimal amounts of fuel to heat spaces. Remember to always use with surge protectors to protect electronic components. For hot water heating, Toyotomis, solar hot water heating and boilers with at least a three-pass heat exchanger will bring the greatest fuel economy. Toyotomis are on-demand water heaters. They are very durable because of simpler components and also have very low fuel consumption.  Solar hot water heating can reduce fuel consumption 65 percent and even higher.  New technologies make solar more usable even with minimal light levels.Viessmann has new solar technology available to connect with existing hot water systems.

•Lastly, boilers are the most multi-purpose. They can be used in large homes and complex floor plans. They are useful for in-floor heating, baseboard heating and solar heating. They can be 90 percent efficient if installing a three-pass boiler. Single pass boilers tend to block up more readily.

Jennie Grimwood has been married to a plumbing and heating contractor for 20 years.  Chris Grimwood has more than 30 years experience in plumbing and heating in New Zealand, the Lower 48 and Alaska and operates Kiwi Mechanical Plumbing and Heating.

The above article is adopted from www.thecordovatimes.com. Please refer to their site for other good information on various other subjects.