Stainless Steel Copper Brazed Plate Heat Exchangers

How Heat Transfer Works

Heat transfer occurs when there is a difference in temperature between two mediums. Heat will travel from the hot source to the cold source. The rate at which the heat transfer occurs at is determined by many factors such as the heat conductivity of the two materials and the difference in temperatures of the two mediums. Convective heat transfer occurs when the materials are moving against each other. Plate heat exchangers have significantly good heat transfer rates because they use metal plates which have high heat conductivity rates and the plates are extremely thin. The plate heat exchangers also achieve high amounts of heat transfer through convective forces with both working fluids. With large temperature differentials, great amounts of heat transfer can be achieved using a plate heat exchanger.

Corrosion

Corrosion is usually how these units will fail. Use fluids with reasonable pH levels to ensure a long lasting life. Hard water will corrode faster than regular water. (Use distilled if possible; Distilled should never corrode in) Salt water will corrode stainless steel very fast. It is recommended to clean the exchanger often if you are using corrosive fluids. Normal usage (non-corrosive fluids) should expect 10-20 years of life. Fluids containing chlorides will corrode the unit quickly.

Applications

This is an extremely popular unit for wood burning furnaces, radiant floor systems, refrigerant systems, straight vegetable oil conversions, beer chilling, air conditioning system and solar water heating systems. It will work for any application in which the desired result is for two fluids (liquid or gas) to exchange heat.

How it Works

Fluid A passes from the port on the left of the heat exchanger through every other channel created by the plates to the opposite end port on the left of the heat exchanger (looking at it the long way). Fluid B passes from the port on the right through the other channels created by the plates and comes out the other port on the right side. The fluids are essentially touching each other through the plates and heat is transferred from the hot fluid to the cold fluid. (but the fluids do not mix)

What Size & How Many Plates?

• More heat exchanger length means much higher efficiency. The longer the better.
• More plates on a heat exchanger adds some extra heat transfer, but is intended to reduce pressure drop. Pressure drop reduces flow rate which reduces heat transfer.
• More width on a heat exchanger allows for much less pressure drop.
• Please see below description for further detailed information

Generally speaking, the more length the heat exchanger has, the more efficiency in heat transfer it has. An infinitely long heat exchanger would allow for the hot fluid to become the temperature of the cold fluid and the cold fluid the hot fluid, assuming perfect energy balance. The more plates and more width the heat exchanger has, the less pressure loss to the fluids flowing through. While adding more plates and width may increase some heat transfer, it is best to add more length for optimal heat transfer gain. More plates and width should be considered when flow rates reach half or more the max flow rate for the particular unit to avoid pressure loss in the fluid flow. Pressure loss means a slower flowing liquid and therefore, less heat transfer overall. In our designs, we typically allow up to a 7.5 psi pressure drop, which is generally accepted as non-interfering with flow rates in a heat transfer application. Most low flow applications experience less than 1 psi drop.  

Maximum Flow Rate for Water with Less Than 7.5 psi Pressure Drop Allowed
Model	Plates	Max Flow (gpm)
B3-12A	10	6
B3-12A	20	12
B3-12A	30	15.5
B3-12A	40	18
B3-23A	20	8
B3-23A	30	12
B3-23A	50	14
B3-23A	60	19
B3-32A	20	14
B3-32A	40	26
B3-32A	60	35

   

Heat Exchanger Sizing

Need a heat exchanger sized for you? Please tell us your email address, fluid media/substance (if using antifreeze, we need to know how much %water and %ethlyene glycol or propylene glycol you have), and 1 of the other 3 variables for the hot/cold fluid parameters. We will size the best heat exchanger for your application based on the given parameters and estimate the result of the other 2 parameters left blank based on that heat exchanger's performance. Please do not provide ranges of numbers. If you are not sure what a parameter will be, give the worst case scenario.