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Afcool Heat Exchangers
 

Onda Heat Transfer Solutions - Brazed Plate Heat Exchangers

The main application of Onda Heat Transfer Products brazed plate heat exchangers is the evaporation and condensation of refrigerant gas in airconditioning and refrigeration plants as well as hot water production in heat pumps and for heat recovery. 
Construction of the brazed plate heat exchangers consists of:

Plate heat exchangers: Stainless steel (316L); Connections: Stainless steel (304L); Brazing material: Copper 99.99 %. The following options are also available on request: Loose or welded mounting supports & insulation
 

Onda - Shell and Tube Condensers

Brazed Plate Heat Exchanger Applications 

With the wide range of 15 different models of the Onda brazed heat exchangers, Onda has the answer to any application, either coming from the refrigeration field (evaporation and condensation of refrigeration gas from 3 to 850 tons) or the HVAC field for all heating-, sanitary water- and airconditioning applications. Onda's Brazed plate heat exchangers are manufactured from raw materials of the highest quality and produced in respect of the European pressure Directive P.E.D. All Onda products are individually selected for your application available in both single and dual circuit configuration.
 

 

 

 

 

  

 

plate of a BPHE
Plate Heat Exchanger Working Principle
Plate Heat Exchangers were first produced in the 1920s and have since been widely used in a great number of sectors.A plate exchanger consists of a series of parallel plates that are placed one above the other so as to allow the formation of a series of channels for fluids to flow between them.  The space between two adjacent plates forms the channel in which the fluid flows.Inlet and outlet holes at the corners of the plates allow hot and cold fluids through alternating channels in the exchanger so that a plate is always in contact on one side with the hot fluid and the other with the cold.The size of a plate can range from a few square centimeters (100 mm x 300 mm side) up to 2 or 3 square meters (1000 mm x 2500 mm side). The number of plates in a single exchanger ranges from just ten to several hundred, so reaching surface exchange areas up to thousands of square meters.Generally, these plates are corrugated in order to increase the turbulence, the thermal exchange surface and to provide mechanical rigidity to the exchanger. Corrugation is achieved by cold forging of sheet metal with thicknesses of 0.3mm to 1 mm.The most frequently used materials for the plates are stainless steel (AISI 304, 316), titanium and aluminium.The corrugation on the plates forces the fluid on a tortuous path, setting a space between two adjacent plates b, from 1 to 5 millimeters.The fluids can cross the channels in series (a less common solution) or in parallel by making counter-current or current configurations.The serial configuration is used when there is a small flow rate for each fluid but high heat jump; the greatest problem is with a high pressure drop and an imperfect counter-current.The parallel configuration with countercurrent channels is used for high flow rates with moderate temperature drops, and is the most widely used.When there is a great difference between the flow rates (or between the maximum permissible pressure drop) of the two fluids, the exchanger can run twice by the fluid with a lower flow (or higher losses) to balance the values of pressure drops or specific flow rates in the channels.One of the most common problems for plate heat exchangers is an irregular supply of the all channels in parallel. In fact, the fluid tends to distribute in greater quantities in the first channels rather than the last ones in order to balance the pressure drop.As the number of plates increases, even distribution declines, resulting in a decrease in the overall performance of the exchanger.

There are two basic types of plate heat exchangers: BPHE-Brazed Plate Heat Exchangers and PHE-Plate Heat Exchangers.
 
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BPHE

 

Brazed plate heat exchangers have no headers, tie bars or sealing gaskets because the plates are furnace brazed at temperatures of 1100°C. During the assembly phase, a sheet of brazing material (generally copper but also nickel) is placed between the plates, the pack is pressed and subsequently baked for some hours. The BPHE exchanger is more compact, lighter and less bulky than one with gaskets.  
The brazing material carries out the function both of the gaskets and the frame. These exchangers are generally used with chevron corrugated plates, which are assembled alternating the corrugation directions in order to create a lattice contact. The crossing points between the corrugations of two coupled plates form a dense network of contact points that confer pressure tightness and induce swirling streams that improve heat exchange. In this way, the turbulence of the fluids is high even at low nominal input speeds and the flow passes from laminar to turbulent for low flow rates.

There are two basic types of plate heat exchangers: BPHE-Brazed Plate Heat Exchangers and PHE-Plate Heat Exchangers

 

 

 

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Onda Heat Transfer Solutions

Afcool is the sole supplier of Onda Heat Transfer Solutions for Africa. Afcool specify and deliver Onda Heat Transfer Solutions to any refrigeration or airconditioning project in Africa. Please contact us for a quote for your HVAC&R project - big or small. Onda Heat Transfer Solutions is a leading Italian company specialising in the production of Heat Exchangers for air conditioning and refrigeration systems.

 

 

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copper replacement coils - smaller
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