FluidPower.Pro

Tag Archive: losses

How to select a hydraulic cooler

At this article, I show my vision on how to:

  • determine the value of the heat needs to be rejected from the system;
  • calculate and select the right cooler size.

…and will provide an example of cooler calculation and selection.

What is a cooler and what is a heat exchanger?

The hydraulic cooler is one of the heat exchangers type. But, what is a heat exchanger? The best definition of the heat exchanger is:

Heat exchanger is a device that transfers heat between two fluids.

The simple sentence but a very good description, because fluids can be either oil, air, water, etc., and because transferred heat can be for either cooling or heating target.

There are two most popular types of heat exchangers in hydraulic systems:

Plate heat exchangers

Plate heat exchanger

Plate heat exchanger

This type has the best value of efficiency/reliability and designed for both cooling and heating applications and a very good for low-viscosity fluids. Pairs of plates can be removed individually for maintenance, cleaning, or replacement. Another advantage of the plate is exchangers is their low initial cost, as well as easy and inexpensive operation.

Fan radiators (air-cooled)

Fan radiators (air-cooled)

Fan radiators (air-cooled)

This type is the only option where water is unavailable or expensive for a delivery. From benefits: low maintenance and operating costs and the only option for oil cooling in mobile applications.

Conduit calculations (pressure losses, velocity)

Pressure losses in the conduit

Pressure losses in the conduit

These calculations can help you to estimate the pressure losses, and flow velocity in the conduit (hose, pipe or tube) and check/correct conduit ID.

Calculations Notes:

  • The recommended flow velocity in conduits you can find at the article Recommended flow velocity.
  • The assumption: pressure losses on elbows, fittings at calculated conduit is zero.
  • Height difference between IN and OUT points needs to calculate hydrostatic pressure what will be added to pressure losses, if IN point is below OUT (use positive value), or subtracted from pressure losses, if IN point is upper than OUT (use negative value). Use value “0” if height difference can be neglected.
  • To find Darcy friction factor there are different formulas used: