BRAZED PLATE HEAT EXCHANGERS
WATER TO WATER HEAT EXCHANGERS

What is a brazed plate heat exchanger? Well a brazed plate heat exchanger is a plate that transfers heat or cold to a second water source. this brazed plate heat exchanger is used to seperate 2 systems from each other and make the most efficient way to transfer heat or cold. this brazed plate heat exchanger allows you to keep one system pressurized and the other non pressurized. the hot water from your heat souce enters one side of the brazed plate heat exchanger and the cold water you need to heat enters the other side of the brazed plate heat exchanger. the waters flow in different directions in seperate plates not mixing. this flow of water through the braze plate heat exchanger makes for the best heat transfer possible. the brazed plate heat exchanger is made from 316 stainless steel and is made for the longest life possible. it can also withstand chemicals as well. the brazed plate heat excahnger is made for potable water as well and is UL listed so you can feel safe that you are buying a quality product. we also give you a LIFETIME WARRANTY against MFG defects as well.

who needs a brazed plate heat exchanger? well anyone who wants to transfer or heat water in their existing boiler or domestic hot water system.

brazed plate heat exchangers should not be used for swimming pools. we do make a pool exchanger made just for this product.

using a brazed plate heat exchanger for infloor heat is ideal as you can use anti-freeze in the infloor heating system under the floor. this will give you piece of mind and save your expensive infloor heat tubes in the event of disaster. it also saves you huge money as you do not have to put anti-freeze in you outdoor wood boiler as i am sure you are aware that this can save you over $1000.00 or more.

brazed plate heat exchangers come in all sizes and with different fitting sizes as well. to size a brazed plate heat exchanger with 1 inch fittings is the most important thing you can do. so if you are not sure what size you need feel free to contact us day or night for help.

SPECIFYING PLATE HEAT EXCHANGERS.

UIT the energy conservation concerns that peaked in the 1970s, HVAC designers began to encounter heat transfer processes for which the familiar shell&tube heat exchanger was not practical. For example, heat recovery from waste streams, such as laundry drains, required closer temperature approaches than shell & tube exchangers could handle, or free cooling systems which typically involved a temperature cross (see diagram at right).

 

THE PLATE EXCHANGER SOLUTION.

What designers needs was a heat exchanger that operated in pure counter flow yet did not take up the space that would be required by a single-pass (counter flow) shell& tube heat exchanger. Such exchangers had been available since the 1920s, but were used mainly for process work where they remained largely unknown to HVAC designers. Their non familiar compact design consisting of thin pressed non ferrous, corrugated plates between which the two streams flow in countercurrent pattern. When their value in HVAC design became recognized they began to appear in the ASHRAE shows, and plate exchanger applications soon followed.

 

FREE COOLING EXAMPLE

A free cooling system from our job files, designed by Greg Gershkovich, PE, is a good example of the plate exchanger advantage in special situations. This was a retrofit project for a major downtown office building in San Francisco with very limited equipment space. The conditions were:

                                    2300 gpm                     67F à 58F

                                    1720 gpm                     65F à 53F

 

This temperature profile contains two characteristics that are anathema to shell&tube exchangers. One is the close 2 degree approach, the other is the temperature cross (65F>58F)

 

SIZING AND SELECTION

The heat transfer surfaces used in plate exchangers are thin, non ferrous plates pressed with a variety of patterns such as washboard or chevron and others. This surfaces encourage turbulent flow with high U factors. The manufacturer will often use combinations of plate designs in the same frame to achieve the specified performance. This involves a vast number of variables which make selection tables – such as those used for shell and tube exchangers – impractical.

Thus selections are routinely made by computer programs that are customized for each manufacturer.

 

CONSTRUCTION DETAILS

Plates are available in 304 or 316 stainless steel, hasteloys, incaloys, titaniums and other pressable non-ferrous materials. A glance at the illustration on the front page shows that the length of the gasketing material around the edges of the plates is considerably longer than would be required on a shell & tube exchanger. Thus it is especially important that the gasket material be compatible with the exchanger fluids and that the gasketing system be designed for easy maintenance. Gaskets are available in nitirle and EPDM elastomers, or various grades of viton, depending on temperature and fluid properties. For most water to water applications not exceeding 275F, nitrile is used. Glueless gasketing in Plate exchangers is used to ease installation and removal.

 

FUTURE CAPACITY

Plate exchangers have the unique characteristic of expandable capacity simply by having additional plates installed when the need arises. If a future increase in capacity will be required, space is left between the follower and the end support to accommodate the required number of additional plates.

 

PLATE MAINTENANCE & REPLACEMENT

Due to highly turbulent flow between plates, scaling is held to a minimum and cleaning is rarely needed in less than six years. When plates need to be cleaned or replaced, the procedure is easily handled by building maintenance staff. Unlike shell and tube maintenance requiring pulling of the entire tube bundle, plates can be cleaned or replaced one at a time.

 

PLATE OR SHELL & TUBE?

Plate exchangers are generally a good choice for operating conditions where shell & tube exchangers are used except when pressures exceed 400 psig or temperature exceed 350F. They are especially good choice if conditions  require a temperature cross or close temperature approach. When conditions require both sides of an exchanger to be stainless steel or other non-ferrous material, plate exchanger will almost always be the less expensive choice.

If space is a consideration (and when isn’t it?), a plate exchanger is especially appropriate. Its footprint is generally a good deal smaller than that of a shell&tube exchanger of equal capacity, and it doesn’t the tube-pull space that adds to shell & tube space requirements.

                                    10 gpm                         190F à 71F

                                    50 gpm                         73.8F <- 50F

 

Effectiveness 119/140 = 85%

 

The practical maximum effectiveness for a multipass shell& tube exchanger is about 75%. So its performance in this case would be:                    

                                    10 gpm                         190F à 85F

                                    50 gpm                         71F <- 50F

 

Effectiveness = 105/140 = 75%

In terms of heat recovery, there is this case an advantage of (73.8-71)(50)(500) = 70,000 Btu/h using the plate exchanger.

 

EFFECTIVENESS

People sometimes speak of plate exchanger as being more “efficient” than shell & tube heat exchangers. This can be misleading if one thinks of “efficiency” in engineering terms, that is, the ratio of energy out to energy in. Any heat exchanger is essentially 100% efficient  in this sense. A better term is “effectiveness” which(in the case of water to water) is the ratio of the larger temperature change to change that is theoretically possible. By this definition , plate exchangers are definitely more effective than shell and tube exchangers.

 

WASTE HEAT RECOVERY

As an example of effectiveness, consider the problem of condensate at 190F with 50 gpm of condensate at 190F with 50gpm of water at 50F. The theoretical maximum temperature rise is (190-50) =140F. Of course that’s not practically obtainable, but 85% of it is not an unreasonable expectation for a plate exchanger. This will result in a the following temperature profile:

 

Published by James Breese & Co. for HVAC&PLUMBING SPECIFIERS
6 Dorman Ave. San Francisco, CA 94121


    

        

HEX HEAT EXCHANGERS


Installation and Operation Guide for Plate Heat Exchangers (Liquid to Liquid, Evaporators and Condensers)
 
  
PIPE INSTALLATION
 
Figures A1 and A2 show the typical installation of an evaporator; B1and B2 of a condenser.
 
Always connect the refrigerant to the side with the soldering connections, (D3, D4) inlet of refrigerant (liquid and high pressure phase) must be attached to the bottom side of the heat exchanger (D3) in case of evaporators; for condensers the gasified refrigerant must enter at the top of the heat exchanger (D4)
 
Liquid side (Glycol Mixture or Water) must be connected to the other side of the unit, always allowing countercurrent flow.
 
For Liquid to Liquid applications, (H type Hex Heat Exchangers) all the connectors should be threaded, in this case connect the hot or cold side at the top or bottom, always allowing the countercurrent flow pattern,
 
 
 
IDENTIFICATION PLATE
 
The identification plate or label gives the basic information of the unit, manufacturing or serial number (1) it also indicates the position of the connections (2).
The model number is followed by the number of plates (3) and the type of connection used, for both the refrigerant side (4) and the liquid side (5).
 
 
MOUNTING
 
Always mount the unit vertically, models smaller than BL26-30 can be mounted directly in the pipes (fig. A) it is recommended to mount larger units on anti-vibration plates (fig. B) or fastened with steel clamps (fig. C) or bolts, when included, (fig. D) if there is risk of vibrations which can damage the connections of the unit, use anti vibration devices such as expansion joints or anti-vibration supports (fig. A). CAUTION: NEVER EXPOSE THE UNIT TO PULSATIONS OR EXCESIVE CYCLIC PRESSURE OR TEMPERATURE CHANGES.
 
 
 
 
 
PROCESS CONNECTION SIDE
 
Connect the pipe using a dynamometric wrench using the tightening limits indicated in the table 1.
 
Brazing – Clean and Polish the surfaces which will be in contact and degrease them, apply flux with a brush. Insert the copper tube into the connection and braze with 40-55% silver mixture, point the flame towards the piping and braze at max. 650C, to avoid internal oxidation, protect the inside of the refrigerant side with a Nitrogen atmosphere
 
 
 
WELDING
 
Protect the unit from excessive heating with a wet cloth around the connection.
 
To limit the heated area make an angle on the tube and connection edges as shown. Use TIG or MIG welding, internal oxidation should be prevented with a small nitrogen flow.
 
 
FREEZE PROTECTION
 
 
For freeze protection use thermostats and/or temperature controls in the spare connections, if any. Connect water side pipes according to the figure when the application is as an evaporator.
 
 
 
INSULATION
 
SCHEMATIC OF INSULATED UNIT
 
 
Insulation is recommended and can be made using extruded insulation sheets (Armaflex or Similar) cut into appropriate sizes and glued together as shown.
 
 
CLEANING
 
Clean with detergents for fatty deposits (without chlorine), for heavier fouling use chemicals compatible with copper and stainless steel, such as formic, citric, acetic or any other organic acids.
 
 
 
FREEZE PROTECTION
 
 
To avoid freezing.
 
-          Use of a filter mesh < 1mm
-          Use antifreeze when the evaporating temperature is close to liquid side freezing.
-          Use a freeze protection thermostat and a flow switch to guarantee a constant water flow before, during and after compressor operation.
-          Avoid operating the unit during pump downtimes.
 
 
TROUBLESHOOTING
 
To ensure the correct performance of the unit, please check the following:
 
-          The unit is correctly connected according to page 2 of this guide.
-          The unit is absolutely clean and free from deposits, increased pressure drop can reveal fouling.
-          The control equipment is correctly adjusted and installed and that freezing does not occur.
 

Snow Melt - Boiler Water to 50% E.glycol
 
 
 
 
 
 
 
 
 
 
 
 
Btu/hr
USGPM
Inlet Temp
Outlet Temp
USGPM
Inlet Temp
Outlet Temp
Model
PSI
PSI
Model
PSI
PSI
Model
PSI
PSI
 
 
 
 
 
 
 
LA14
HOT SIDE
COLD SIDE
LB31
HOT SIDE
COLD SIDE
LC110
HOT SIDE
COLD SIDE
20,000 Btu/hr
1.37
180F
150F
1.52
100F
130F
LA14-6
0.88
0.92
-
-
-
-
-
-
30000 Btu/hr
2.06
180F
150F
2.28
100F
130F
LA14-6
1.91
2.01
-
-
-
-
-
-
40,000 Btu/hr
2.75
180F
150F
3.03
100F
130F
LA14-6
3.34
3.50
-
-
-
-
-
-
50,000 Btu/hr
3.44
180F
150F
3.79
100F
130F
LA14-6
5.13
5.38
-
-
-
-
-
-
60,000 Btu/hr
4.12
180F
150F
4.55
100F
130F
LA14-10
2.74
2.78
-
-
-
-
-
-
70,000 Btu/hr
4.81
180F
150F
5.31
100F
130F
LA14-10
3.70
3.87
-
-
-
-
-
-
80,000 Btu/hr
5.50
180F
150F
6.07
100F
130F
LA14-10
4.78
5.01
-
-
-
-
-
-
90,000 Btu/hr
6.19
180F
150F
6.83
100F
130F
LA14-20
1.63
1.71
LB31-10
4.80
5.10
-
-
-
100,000 Btu/hr
6.87
180F
150F
7.59
100F
130F
LA14-20
2.00
2.10
LB31-20
1.58
1.68
-
-
-
125,000 Btu/hr
8.59
180F
150F
9.48
100F
130F
LA14-20
3.08
3.23
LB31-20
2.42
2.57
-
-
-
150,000 Btu/hr
10.31
180F
150F
11.38
100F
130F
LA14-20
4.39
4.59
LB31-20
3.42
3.63
-
-
-
175,000 Btu/hr
12.03
180F
150F
13.27
100F
130F
LA14-30
2.87
2.99
LB31-20
4.59
4.87
-
-
-
200,000 Btu/hr
13.74
180F
150F
15.17
100F
130F
LA14-30
3.71
3.88
LB31-30
2.77
2.94
-
-
-
225,000 Btu/hr
15.46
180F
150F
17.07
100F
130F
LA14-30
4.66
4.87
LB31-30
3.47
3.67
LC110-20
1.54
1.63
250,000 Btu/hr
17.18
180F
150F
18.96
100F
130F
LA14-30
5.72
5.98
LB31-30
4.23
4.49
LC110-20
1.88
1.99
275,000 Btu/hr
18.90
180F
150F
20.86
100F
130F
LA14-40
4.27
4.45
LB31-30
5.08
5.38
LC110-20
2.25
2.39
300,000 Btu/hr
20.62
180F
150F
22.76
100F
130F
LA14-40
5.06
5.27
LB31-40
3.53
3.74
LC110-20
2.66
2.82
350,000 Btu/hr
24.05
180F
150F
26.55
100F
130F
LA14-50
4.87
5.07
LB31-40
4.73
5.01
LC110-20
3.56
3.78
400,000 Btu/hr
27.49
180F
150F
30.34
100F
130F
LA14-60
4.93
5.12
LB31-50
4.08
4.32
LC110-20
4.59
4.87
450,000 Btu/hr
30.93
180F
150F
34.13
100F
130F
-
-
-
LB31-50
5.11
5.41
LC110-30
2.69
2.87
500,000 Btu/hr
34.36
180F
150F
37.93
100F
130F
-
-
-
LB31-60
4.53
4.49
LC110-30
3.29
3.48
600,000 Btu/hr
41.23
180F
150F
45.51
100F
130F
-
-
-
LB31-70
4.94
5.22
LC110-30
4.65
4.93
700,000 Btu/hr
48.11
180F
150F
53.10
100F
130F
-
-
-
LB31-80
5.33
5.62
LC110-40
3.67
3.88
800,000 Btu/hr
54.98
180F
150F
60.68
100F
130F
-
-
-
LB31-100
4.88
5.14
LC110-40
4.73
5.01
900,000 Btu/hr
61.85
180F
150F
68.27
100F
130F
-
-
-
LB31-120
4.74
4.98
LC110-50
3.95
4.18
1,000,000 Btu/hr
68.72
180F
150F
75.85
100F
130F
-
-
-
LB31-130
5.26
5.51
LC110-50
4.83
5.11