Technical Help
American Industrial provides the following technical information in an ongoing effort to provide technical assistence to persons that have a basic understanding of heat transfer. As with any engineering disipline, some mathmatical skills are required to do many of the formulas for calculation that are provided. It is important that accurate calculations be applied before choosing and purchasing a heat exchanger. If you are unsure of the proper size of cooler required, or if you do not understand the formulas contained in the following subject matter, contact our engineering dapartmant for specific application help.

Application Basics
There are numerous hundreds of applications that heat exchangers can be applied into, but for the most part only a few configurations come up repeatedly. Following will describe several configurations for hydraulic, lubrication, engine coolant, steam heating of liquids, and compressor air cooling. We can summerize most of the applications into two catagories. The first one is direct cooling and the second is indirect cooling.

Direct cooling normally applies the heat exchanger directly into the fluid line after it has been heated and before it reaches a reservoir or other device. Normally an example of a direct cooling application would be a cooler in the return line of an open loop hydraulic system. All of the system oil is cooled before it re-enters the reservoir, thus holding the reservoir at a constant temperature. A second example of direct cooling would be in compressed air line exiting a screw compressor. The air is cooled before it enters a receiver tank or the process. In either case it is normally more efficient to cool the oil in this manner since it will allow for greater temperature difference between the fluid being cooled and the coolant.

Examples
 
 

Indirect cooling applies mainly to systems that for good reason (ie..vibration, pressure, reduced available flow, etc...) cannot directly cool the oil. This is normally refered to as an off-loop system, 'kidney loop", recirculation loop, filter loop, etc...., and generally refers to closed loop systems. Indirect cooling is normally found on mobile equipment or systems with large flow requirements that make it unrealistic to apply cost effective cooling. Although the indirect cooling is less efficient than the direct cooling in many circumstance there is no choice.
 
 

Required information
Regardless of your application your system will heat one fluid while cooling the other. The basic theory in heat transfer weather cooling with water or air is "balance", the equations must balance to produce accurate results. The following information will help determine many of the required pieces of information needed to size a heat exchanger to heat or cool your application.

Hydraulic & Lubrication Systems
1) Electric motor horsepower of prime mover pump or heat to be removed if known. If more than one prime mover, add them up.
2) System (oil) operating pressure.
3) Process (oil) system flow rate or flow rate to heat exchanger.
4) Process (oil) temperature entering or exiting the heat exchanger or desired reservoir temperature.
5) Oil type. (ISO 32, 46, 68, etc...)
6) Cooling media. (water, air)
7) Average cooling media temperature & worse case temperature. (ie.. 100F air, 95F water, etc...)
8) Available volume cooling media. ( 10gpm, 20 gpm, 30gpm, etc...)
9) Material requirements.
10) Physical size requirements.
11) If air cooled, fan drive. ( Electric, hydraulic, pneumatic, etc...)
12) Location of cooler. (Return line, off loop)

Steam Heating
1) Type of fluid to be heated. If exotic obtain specific heat transfer information such as, specific heat, conductivity, viscosity, and density.
2) Beginning & ending temperatures of fluid to be heated.
3) Flow rate of fluid to be heated.
4) Operating pressure of saturated steam in PSI.
 

Quick sizing

Shell & Tube

Step1.
                 Industrial  Formula                                                                                                          Example
Electric motor prime mover HP x .3 = HP heat                                                             40 HPelectric x .3 = 12 HP heat

                  Mobile Formula                                                                                                              Example
Main system flow GPM x operating pressure PSI                                                        23 gpm x 3000 psi
------------------------------------------------------------------- X .3 = HP heat                           ------------------------- X .3 = 12 HP
                            1714                                                                                                                         1714

HP x 2545 = BTU/hr heat                                                                                                  12 x 2545 = 30,540 BTU/hr