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Brazed Plate Heat Exchangers

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Brazed Plate Heat Exchangers 

Brazed heat exchangers (BPHE) are a compact heat exchanger that consist of corrugated metal plates that are brazed together to form a single unit. The brazing process involves melting a filler material, typically copper-based alloy (Stainless or Nickel are available), between the plates to create a strong and leak-proof joint.

The main advantages of brazed heat exchangers include their high heat transfer efficiency, compact size, and reliability.

Features

Compact Size - Brazed heat exchangers corrugated plates create multiple flow channels, maximizing the heat transfer surface area within a small footprint. This makes them ideal for applications where space is limited.

Efficient Heat Transfer - The corrugated plates in a brazed heat exchanger create turbulence in the fluid flow, enhancing heat transfer efficiency. The turbulent flow promotes better mixing of the fluids and minimizes the formation of stagnant zones, leading to improved heat transfer rates.

High Thermal Efficiency - The brazing process used in the construction of these heat exchangers ensures a highly conductive joint between the plates.

Reduced Fouling - The design of brazed heat exchangers with smooth and continuous surfaces minimizes the potential for fouling. The absence of gaskets or crevices reduces the likelihood of accumulated debris or scale, resulting in lower maintenance requirements and improved overall performance.

Applications

  • HVAC systems
  • Refrigeration
  • Process cooling
  • Industrial heating and cooling
  • Liquid-to-liquid and gas-to-liquid heat transfer processes

Flow principle

The basic flow principle in a brazed plate heat exchanger is parallel to achieve the most efficient heat transfer process. In a single pass design, all connections are located on one side of the heat exchanger, making installation very easy.

The flow principle of a brazed heat exchanger is based on the counter-current flow configuration, where the two fluids involved in the heat transfer process flow in opposite directions.

Connections

 

 

 

Single circuit BPHE data

Model Design Pressure (bar) A B C D   E Channel Volume L
BL6   30/45 55 119 26 91 7+1.29N   0.0053
BL12   30/45 76 152 42 120 7+1.29N   0.01
BL13   30/45 76.5 194 40 154 8+1.05N   0.0093
BL14   30/45 76 206 42 172 8.6+2.3N   0.027
BL14D   10 71 186 40 154 7.5+2.26N   0.026
BL15A   10 83 193 40 154 7+2.26N   0.029
BL14W   30/45 78 206 42 172 7.5+2.26N   0.028
BL16   30/45 78 206 42 172 7.5+2.26N   0.028
BL17   30 85 202 39 153 24.5+2.31N   0.031
BL18   10 91 210 50 162 9+3.3N   0.053
BL20   30/45 77 317 42 282 8+2.31N   0.042
BL20W   30/45 75 315 42 282 11+2.25N   0.042
BL21   45 76 312 42 278 6.6+1.23N   0.021
BL25   30/45 92 322 39 268 8+1.55N   0.032
BL26   30/45 109 310 50 250 10.6+2.35N   0.057
BL26W   30/45 106 306 50 250 10.9+2.25N   0.057
BL30   30/45 124 304 70 250 12+2.31N   0.069
BL50   30/45 108 525 50 466 9.5+2.31N   0.097
BL60   30/45 119 526 63 470 9.4+2.31N   0.11
BL95A   30/45 187 616 92 519 10.2+2.31N   0.2
BL95B   30/45 187 616 92 519 11+2.81N   0.25
BL95C   30/45 187 616 92 519 11+2.81N   0.25
BL120   30/45 245 529 174 456 12.4+2.31N   0.24
BL122   30/45 246 529 174 456 12.4+2.31N   0.24
BL125   30 248 530 159 441 12+1.95N   0.2
BL180   30/45 256 846 160 750 8+2.31N   0.4
BL190   15/21/30 307 698 179 567 9+2.81N   0.49
BL195   15/21/30 306 694 179 567 11.2.31N   0.39
BL200   15/21/30 320 740 188 603 12+2.75N   0.54
BL350   30 304 981 179 854 11.5+2.31N   0.55
BL600   15/21 436 140 220 1190 16.3+2.8N   1.4

*N means the plates number

Model   Design Pressure (bar) A B C D F E Channel Volume L
BL100   30/45 248 496 405 157 405 7+1.29N     0.2
BL100E   30/45 248 495 411 159 369 10+2.09N     0.2
BL100EW   30/45 243 491 411 159 369 10+2.03N     0.2
BL130AS   45 293 532 397 177 399 12.3+2.05N  0.27/0.24
BL210   30/45 320 737 568 205 631 8+2.61N     0.5

*N means the plates number

A dual system BPHE (Brazed Plate Heat Exchanger) refers to a brazed plate heat exchanger that is specifically designed to accommodate two separate and independent fluid circuits within a single compact unit. It consists of two separate sets of plates, each forming a distinct flow path for a different fluid.

Part-load efficiency also decreases with these arrangements, because the flow arrangement means that only 50% of the secondary fluid undergoes heat exchange. The evaporation temperature at part load may therefore decrease, reducing system efficiency and increasing the risk of freezing. Instead, true dual technology BPHEs have two independent refrigerant circuits combined with a common secondary fluid circuit. A true dual heat exchanger is shown in Figure 1.

A true dual BPHE running with both circuits active operates no differently from a high-efficiency single circuit evaporator with full contact between refrigerant and secondary fluid.

Even if one refrigerant circuit is closed, i.e. half-load operation, all secondary fluid channels remain in contact with the active refrigerant channel (see Figure 2). All the secondary fluid will still receive heat exchange, and the leaving water temperature will therefore be the same as for full-load operation provided the water flow is also halved. This allows the part-load evaporation temperature to remain at a high level, resulting in increased efficiency at part load. Because secondary fluid channels will surround the active refrigerant circuit, the evaporating process will also remain fully stable.

For a schematic system sketch of a true dual system, see Figure 3.

Asymmetrical brazed plate heat exchanger

The term "asymmetrical" refers to the fact that the two sides of the heat exchanger have different geometries, specifically different channel depths. This design is often used when the heat transfer requirements on the hot and cold sides are different.
In an asymmetrical brazed plate heat exchanger, the hot fluid flows through channels with a larger depth, which allows for greater heat transfer. The cold fluid flows through channels with a smaller depth, which offers less resistance to flow, reducing the pressure drop.
This design is particularly useful in applications where one fluid is at a much higher temperature than the other, such as in a condenser or evaporator.

The asymmetrical design allows for efficient heat transfer while minimizing the pressure drop on the lower temperature side, improving overall performance.
Studies have shown that an asymmetrical brazed plate heat exchanger can provide up to 15% higher heat transfer rates and up to 30% lower pressure drops than a regular design brazed plate heat exchanger, depending on the specific operating conditions and application requirements. However, these percentages are approximate and may vary depending on the specific application and heat exchanger design.

 

 

 

Model Design Pressure (bar) A B C D E Channel Volume L
BL37AS   30/45 121 332 68 279 11.3+1.55N 0.05/0.04
BL40AS   30/45 119 376 72 329 12+1.55N     0.044/0.066
BL61AS   30/45 118 524 63 470 10.5+1.91N     0.092/0.075
BL95AS   30 185 613 92 519 11.3+2.07N 0.2/0.16
BL150AS   21/30 266 696 122/131 564/545 10+2.31N 0.36/0.3