Efficiency is King – Optimal Integration of Electrical Thermal Management (Part 2)

In the first part, we discussed the challenges of electrification of large vehicles and construction machinery. One essential element is the electronic thermal management for batteries, components, and the interior. In the second part, Charles Byrd, systems expert at Webasto, explains what is important for integration.

Depending on the design and the required heating and cooling capacity, there are various possible combinations for the interaction of integrated electrical thermal management (eTM) and electronic battery thermal management (eBTM) in large vehicles and construction machinery.

It can be worthwhile to completely integrate the eTM and eBTM. As in this example: “On an excavator, the cabin requires a heating and cooling capacity of about 7kW. With an average energy consumption of about 40kW, the cabin would require almost 25 percent of the total energy output. This is where a combination of eBTM and eTM pays off,” Charles Byrd estimates.

Webasto's scalable approach shines in this area, as it separates the thermal management of the battery from the cabin. This supports the manufacturer in series production and accelerates the time-to-market. “For example, if a large fire truck has two eBTMs cooling and heating the batteries, we recommend the decoupling of the cabin air conditioning if the focus is on accelerating time to market,” says Charles Byrd.

Technically demanding: The best combination is always a compromise

In other situations, it makes sense to use only one eTM as a cooling and heating unit in heat pump mode. “An eTM can generate up to 10kW of cooling power with the appropriate refrigerant. For smaller vehicles, you need about 2kW of cooling when the vehicle is in operation, and another 4kW is needed for the cabin. But if the vehicle is not in use, is being charged, and the cabin may be empty, then all the cooling power can be used for battery cooling,” says Charles Byrd.

The integration of thermal management is a highly complex and technically demanding task. Nevertheless, there are a few basic technical correlations: If, for example, the power demand of the powertrain or the charging current represents a constantly high thermal load, there is little heating or cooling power left over that can be shared with other vehicle components.

 However, a large amount of waste heat from the powertrain and power electronics can also be used to heat the interior, for example. “One particular challenge in recovering waste heat from vehicle components is the generating of the heat at different temperatures, which are constantly changing during operation,” says Byrd.

Webasto experience leads to the optimal solution

In practice, there is no single solution that fits all. This is why the experience and technical expertise of Webasto's thermal experts are so valuable when it comes to optimal integration.

In several projects with manufacturers, Webasto works with existing specifications, such as the required heating and cooling capacity, the available installation space, and the weight distribution, which cannot be changed. Each project has its own characteristics. However, Webasto has designed the electrical thermal management systems in a modular way such that the appropriate thermal management solution can be integrated into the system in a short time.