Cooler series for marine hydraulic systems improves efficiency, saves costs

In light of the importance of installing the correct cooler for particular hydraulic systems, motion and control technologies diversified manufacturer Parker Hannifin’s Accumulator and Cooler Division Europe (ACDE) is developing the MAC air oil-cooler series, which provides significant benefits for hydraulic systems with marine applications.

Based on the proven efficiency of Parker’s LAC series, the new range of MAC coolers has been designed to withstand the challenges of marine environments and is engineered for near-shore and offshore applications. The coolers provide cooling capacity of up to 300 kW and feature a one-piece motor bracket with improved aerodynamics, as well as a fan housing with an adapted design to reduce the risk of corrosion.

Extensive marine specifications were adhered to with regard to the design of the electric motor and lower noise levels make the series more environment- and user-friendly.

Parker coolers engineering manager Erwan Jagueneau notes that, with the dual forces of increasingly stricter environmental regulations and an unappeasable desire to reduce operating costs governing industries, research and development into increasing the efficiency of hydraulic systems is ongoing.

Despite the advances that have been made in the development of new technologies, he highlights that some energy losses in hydraulic systems remain inevitable through factors such as fluid friction, pressure drop, lamination and fluid compression.

He explains that power losses are converted to heat, which is transferred through the hydraulic system. “Temperature management in hydraulics, therefore, is an essential factor in running the system at its optimum efficiency; however, it is often neglected.”

Heat exchangers or coolers are generally considered only as add-ons at the end of a hydraulic system’s conception. However, Jagueneau notes that the selection of the correct cooling unit requires detailed information of the hydraulic system’s application and heat-dissipation parameters. A more thorough consideration of cooling in the early stages of the hydraulic system’s design can, thus, improve the choice of cooler, potentially improving the whole system’s operational efficiency and cost-effectiveness.

“Hydraulics engineers should heed the effect that optimal temperature management can have on a hydraulic system’s overall efficiency. Overheating or selecting the incorrect cooling technology can result in high operational costs, unnecessary energy consumption and costly maintenance for companies.”

He explains that the installation of an undersized cooling system is a common problem in the thermal control of a hydraulic system, resulting from underestimating the system’s heat dissipation. This usually stems from incorrect assumptions regarding hydraulic cycles, the exothermic function of the hydropneumatic accumulator, lamination and frictions.

Without an efficient cooling system, a chain of damaging reactions takes place in the hydraulic system, Jagueneau outlines, adding that the hydraulic fluid stabilises at a higher temperature than it should, consequently reducing the fluid lubrication capability of the system.

This causes accelerated wear of mechanical parts and, moreover, generates particles that impact on oil cleanliness, which, in turn, starts to damage servo valves and other sensitive components. The more components are eroded, the more abrasive the hydraulic fluid becomes. Continuous operation at a high temperature, moreover, causes ageing of rubber seals.

The life span of the hydraulic system is negatively impacted on when the correct cooling system is not installed; operators face the risks of unexpected leaks, unplanned downtime because of system failure, excessive maintenance costs and loss of productivity, Jagueneau explains.

An oversized cooling system can also be problematic, he notes, pointing out that the oil will probably be at a lower temperature than is optimal, increasing its viscosity and, subsequently, causing the system’s pressure to drop and increasing power consumption.

Working closely with the company’s suppliers to validate the design, Parker is finalising its MAC cooler series for marine applications, which will be launched in South Africa in January.

Parker Sales Company South Africa hydraulics sales manager Keith Mullen is excited to launch the product to the marine market. “Parker distributors will provide value-added service in this challenging marine market.”

The range includes four high-cooling-capacity models that offer low installation and operating costs and are easy to maintain. The coolers are compact, lightweight and retrofittable to any marine hydraulic system.

Jagueneau is optimistic about the reception of the series, noting that it has received much interest, as a result of its prelaunch at the Shipbuilding, Machinery and Marine Technology trade fair, which was held in Hamburg, Germany, last month.