BPHEs in wind power stations


The world’s windmills already produce 13,000 MW of electrical power, and experts consider that some 10% of the world’s energy demand could be supplied by wind power in the future. 

There is an ideal application for SWEP’s rugged and efficient BPHEs in every windmill: not directly in the production of electricity, but for cooling the vital oil that lubricates the mechanical power transmission and control systems.

The problem
A gearbox at the top of the windmill controls the velocity of the rotor and transmits mechanical power. The transmission oil that lubricates the gears gets hot, and must be cooled to maintain its performance and protect the gearbox. In a single-circuit solution, the oil is cooled by being pumped through a large air coil. However, this requires a large, expensive pump and air coil, and is neither efficient nor convenient, particularly when windmills are typically located in exposed and/or remote positions.

The solution

Cooling performance can be improved cost-effectively and within a smaller envelope by using a SWEP BPHE (e.g. a B57). The BPHE solution replaces the single large oil circuit with two smaller circuits, one for oil and one for ethylene glycol, with several advantages.

Heat transfer generally is improved because of the highly turbulent flow through each BPHE. Furthermore, the pumps and the air coil required for the two-circuit solution are smaller and less expensive to buy and run.

This is because ethylene glycol has better heat transfer properties than lubricating oil, and this system requires less ethylene glycol to flow through the air coil.

System description
During operation, the temperature of the transmission oil increases, and must be reduced to maintain proper lubrication of the gearbox. The oil is pumped through the BPHE where it is cooled by a glycol/water solution.

The glycol/water solution is cooled in turn by passing it through a relatively small coil fitted with flanges that present a large area to the air for cooling.

In this solution, SWEP BPHEs offer:

  • High efficiency even at low flow rates
  • Savings on buying and operating pumps and air coils
  • Ruggedness and simplicity for minimal maintenance
  • Compactness for lower overall space requirements