BITZER Launches OWD Water-Cooled Oil Cooler Series with Capacity up to 300 kW

BITZER has expanded its component portfolio with the OWD water-cooled oil cooler series, offering a maximum capacity of up to 300 kW and a new disc-and-doughnut baffle design aimed at improving heat transfer while keeping pressure loss to a minimum.

Portfolio coverage and refrigerant compatibility

The OWD series spans the capacity range of all BITZER screw compressors in both single and parallel operation. It is compatible with a range of synthetic refrigerants, including HFC, HFC-HFO blends, HFO and hydrocarbons. Although the series was specifically developed for BITZER's semi-hermetic HS and open-drive OS screw compressors, it also provides a reliable solution when paired with products from other manufacturers. The range comprises 17 product variants in 2-pass and 4-pass configurations, allowing adjustment to the specific requirements of different applications. Nominal test conditions are an oil temperature drop from 80 °C to 50 °C, a water temperature rise from 30 °C to 35 °C, and highly viscous BSE170 oil.

Baffle technology and heat-transfer gains

The defining feature of the OWD series is its use of disc and doughnut baffles, which create a symmetric flow pattern for even oil distribution across the cooler tubes. This design improves heat transfer on the oil side, reduces flow surges and minimises unwanted turbulence, contributing to higher efficiency, greater operational stability and an extended service life. Baffle distances are adjusted for each cooler size so that flow velocity remains optimised, achieving a balance between heat transfer and pressure drop even in larger units. The baffles are temperature-resistant and withstand temperatures above +150 °C.

Compared with the predecessor OW series, the OWD design reduces dead space inside the heat exchanger, increasing the effective use of the entire tube surface and raising heat throughput. The optimised space requirement also allows a higher number of tubes to be integrated, enabling ultra-high power density. BITZER states that calculations show the new series reduces CO₂-equivalent emissions by more than 40 % relative to the OW predecessor. The OWD series was developed using computational fluid-dynamics (CFD) simulations and extensive laboratory experiments, specifically for refrigeration and heat-pump applications.

Operating range and certifications

The OWD oil coolers are rated for the following conditions:

• Oil temperature: –20 °C to +150 °C
• Oil pressure: up to 32 bar
• Water temperature: –20 °C to +95 °C at 10 bar
• Water medium: fresh water or seawater

The units meet stringent requirements for temperature resistance, pressure strength and corrosion protection, and comply with CE-PED, SELO CML, BV and DNV certifications. This qualifies them for heat-pump and low-temperature applications in maritime and industrial sectors as well as in the high-temperature range.

Selection via BITZER SOFTWARE

The OWD series can be combined with BITZER open-drive OS and semi-hermetic HS screw compressors within BITZER SOFTWARE. The platform allows users to select a compressor manually or receive a recommendation based on capacity, operating conditions and specific requirements. Once a compressor is specified, the software calculates the required cooling capacity and, where applicable, recommends a suitable oil cooler. Users can also select the "External oil cooling" option manually in the "Additional cooling" section. All relevant technical data are presented in a straightforward format, and temperatures can be customised on a secondary page to ensure optimal coordination of components.