As the name of the heat exchanger implies, this device has a duty of heat exchange between two fluids. the fluids can be water, gas, oil, air, etc.
Types of heat exchangers in central heating and air conditioning system according to building type are as follows :
Shell and tube heat exchangers are very popular in air conditioning, pools, and even chemical industr...
As the name of the heat exchanger implies, this device has a duty of heat exchange between two fluids. the fluids can be water, gas, oil, air, etc.
Types of heat exchangers in central heating and air conditioning system according to building type are as follows :
Shell and tube heat exchangers are very popular in air conditioning, pools, and even chemical industries. As indicated by their name, they include a high-pressure, large cylindrical tank (shell) housing a number of tubes. The liquid moves through the pipes and hot water or steam passes over these tubes inside the shell. A large number of the said tubes and their great contact surface effectively transfer heat to the liquid in the tube and heat it up.
Shell and tube is the most popular type of heat exchangers which are categorized into different sub-types based on the number of tube and shell passes. The simplest kind features a single pass of tube and shell (figure below). These heat exchangers usually have a partition inside, also known as baffles, which creates turbulence and lateral-velocity in the flow and therefore increases the convective coefficient of the fluid in the shell. Heat exchangers with baffles usually have a single pass of shell and two passes of tubes or two passes of shells and four passes of tubes. The fluid is directed perpendicular to the tubes between the two adjacent baffles.
U-shaped shell and tube heat exchangers are the cheapest of their kind as they only require a single tube plate. The tube interior cannot be cleaned mechanically due to the sharp U-turn. These exchangers use an even number of tube passes and are not limited in terms of thermal expansion.
A. In shell and tube heat exchangers, the tubes are responsible for heat exchange, such that the two sides of a tube are in contact with fluids at different temperatures. They act as a separating element and come in different sizes. They are mostly made of copper, however, can also be manufactured from stainless steel, nickel, aluminum, brass, or titanium. Considering the heat transfer coefficients of the fluids inside and outside of the tube, fins, and baffled tubes can be employed on the side with a lower coefficient, which also imposes some costs.
B. The shell and the tube sheets hold the tubes and connect the inlets and outlets. Tube thickness depends on the operating pressure and shell thickness.
The shell is normally made of stainless steel as it needs to offer the lowest level of heat transfer while providing high-pressure tolerance. The shell will hold the water inlet and outlet, the hanging hook, discharge valve, sensor safety valve, and other components.
Different flow regimes can exist on the shell and tube sides in these exchangers. The regime types are selected according to attributes such as heat transfer surface, operating pressure, coil pressure drop, manufacturing process, corrosion-control costs, and maintenance. Baffles are used to increase the heat transfer coefficient at the shell side and to better secure the tubes.
Gasketed plate heat exchanger
Welded plate heat exchanger
The heat exchangers are also used in the swimming pools, sauna, and jacuzzi heating systems. In the picture seen below, the location of the heat exchangers, as the heating system of the pool, along with other pool equipment is precisely determined.
Due to its steel body, Plate heat exchangers are simply used to heat the pool water. However, it should be noted that the heat exchanger should be placed after the filter and before disinfecting equipment such as chlorinator.
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Plate heat exchanger | shell and tube heat exchanger | |
Temperature intersection | Not possible | possible |
Operating temperature difference | About 1 centigrade | About 5 centigrade |
Multitasking | possible | Not possible |
Pipe fittings | one direction | multi directions |
Heat transfer coefficient | 3-5 | 1 |
Operating Weight ratio | 1 | 3-10 |
Storage volume | low | high |
Space coefficient | 1 | 2-5 |
boiling | No | Yes |
Vibration sensitivity | Not sensitive | sensitive |
gasket | On each plate | On each lid |
leakage detection | easy | hard |
Access for inspection | No limit on each side | limited |
Disassembling time | Up to 15min | From 60 to 90 min |
Repair | Replacing plates or gaskets | Changing or blocking tubes |
Heat value correction | Easily by adding or removing plates | complicated |
Sediment Coefficient | 0.1-0.25 | 1 |
Important to determine the pressure drop of water flowing through the coils or heat exchanger plates (and air passing through the heat transfer coils) in order to calculate the head of the pump circulator or the static pressure of the aeration fan.
Also correct calculation of inlet and outlet water pipe diameter of heat exchangers with water as working fluid leads to the deliverance of sufficient fluid enabling needed heat transfer in the heat exchanger.
The following diagram can be used to calculate the diameter of steel tubes in heating and cooling systems.
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M² = 10.764 Ft.²
Ft.² =0.0929 M²
1 Atm. =14.7 PSI
Ft.² 0.1309 = inch 8/3 per foot of pipe length
1Gal .(am.)=3.785 Lit
Ft.² 0.1309= inch 2/1 per foot of pipe length
1 Atm=the height of water tower10.33
1M³ = 264.2 Gal.(am)
1M³ =35.315 Ft.³
Hepaco Plate Heat Exchanger HP-1200
Warranty : 1 year After-sale Services : 10 years
Hepaco Plate Heat Exchanger HP-300
Warranty : 1 year After-sale Services : 10 years
Hepaco Plate Heat Exchanger HP-100
Warranty : 1 year After-sale Services : 10 years
Hepaco Plate Heat Exchanger HP-60
Warranty : 1 year After-sale Services : 10 years
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