Manufacturer uses Simcenter Amesim to design diesel engines faster and more efficiently

Meeting new emission standards

Non-road diesel engines are robust and durable machines that deliver strong output power. For more than a century, the German company Hatz Diesel (Hatz) has developed and produced generator sets and industrial engines for construction machinery equipment. The Hatz tradition embraces innovation, quality and strong customer relationships. Top industrial companies rely on the rugged and powerful Hatz engines.

However, the power generation and construction equipment industries are undergoing profound changes that severely affect engine manufacturing companies.

First, strict regulations emanating from the European Union and North American governments are challenging engine manufacturers to develop motors that drastically cut toxic gas emissions. According to the United States Tier IV final emission standard for non-road diesel engines, current nitrogen oxides and particulate matter emissions should be reduced by 90 percent by 2015.

Second, in addition to emission reduction, engine manufacturers are being asked to provide the industrial world with highperformance, reliable and durable machines that are more energy-efficient, lighter, less noisy and vibrate less. Meeting and balancing these conflicting but unavoidable requirements is the challenging task facing Hatz engineers.

Developing deep system knowledge

“The complexity of engine systems has dramatically increased in recent years,” says Tobias Winter, head of the simulation department at Hatz. “In order to design new engines, very deep system knowledge is required. In fact, in order to evaluate the effects of even minor changes in subsystems of the full engine, we need advanced simulation tools. Gathering deep system knowledge is largely advanced by using simulation techniques.”

Winter, who has been a driver of change at Hatz, manages a four-person department that uses Simcenter Amesim™ software from Siemens Digital Industries Software on a nearly daily basis. Before the turn of the 21st century, the company outsourced its simulation tasks. As market demands evolved, Hatz management acknowledged the need to acquire comprehensive internal simulation knowledge. With Winter on board, the company uses Simcenter Amesim for system simulation.

“Think about the downsizing trend: it also impacts our industry,” says Winter. “We are required to deliver engines that provide strong output power but consume less fuel. It’s inconceivable today to design new turbocharged engines without the help of high-performance simulation software. A multidisciplinary system simulation platform like Simcenter Amesim gives us a clear view on all mechanical, hydraulic and thermal aspects of the design.”

Embracing water-cooled innovation

Hatz is continuously innovating to provide top-of-the-line engines that have a lower environmental impact. In 2009, the company started the development of a downsized, water-cooled, turbocharged, common rail injection, 4-cylinder diesel engine.

Traditionally, Hatz has developed and marketed air-cooled engines that are praised for their robustness and easy maintenance.

In spite of higher maintenance costs, water-cooled engines offer important advantages over air-cooled ones. Thanks to its good thermal properties, water transmits heat over greater distances with less volumetric flow. The water jacket around the engine also dampens mechanical noises, making the engine quieter.

Sizing the cooling systems of industrial engines is particularly difficult. Compared to automotive engines, industrial engines demand more cooling power and require a permanent fan operation to cool down. The cooling circuit greatly influences engine performance and efficiency. It is crucial from the earliest stage to develop proper sizing of the cooling circuit; the goal is to achieve optimal engine performance without over-engineering any parts.

The design of a cooling system is complex. First, it should precisely outline the complex hydraulic network. Second, the multiple subsystems, such as pump, piping and heat exchangers, need to be optimally designed and interconnected.

“Simcenter Amesim lets us achieve the multidisciplinary optimization of each component and of the full cooling system,” says Winter. “We can quickly evaluate different schemes to find fast answers to our toughest engineering questions.”

Getting fast answers

Hatz engineers employ Simcenter Amesim at different stages of the product development process. In the initial phase, in which no hardware or hardware parts are available, they focus on the sizing of the hydraulic components.

They define the first system settings in the software using some test data from previous designs to complement the model. They integrate pump characteristics, forecasted pressure loss and possible heat exchanger pre-designs to obtain a 1D model of the cooling circuit.

When the first hardware sample is available, it is tested on a cold water test bench to measure the volumetric flow rates in the branches of the cooling circuit. The measured data is used to validate the 1D model. In a second step, this model is extended to include thermal characteristics.

The thermo-hydraulic model of the cooling circuit is connected to a 1D oil circuit model and both are coupled with the heat exchanger. By relying models created using Simcenter Amesim, Winter is able to answer multiple engineering questions in short order: “With my 1D model in hand, I can imagine all possible scenarios and quickly try them out.

“For example, if we think about making the engine even quieter, we can consider lowering the fan RPMs. As the coolant pump and the fan are mounted on the same shaft, pump RPMs are also decreased. How does this affect the thermal condition of the engine under certain operating conditions? Depending on my engineering needs, I check my design variants and question my model.

“If I reduce the engine speed while maintaining the same output power, what is the impact on the cooling system? If I decrease the size of the lubrication pump and thus the flow rate through the oil heat exchanger, how will this affect the temperature? Do I need a bigger heat exchanger? How do I size it? All these questions can be answered with system simulation.”

Tackling critical challenges

The Hatz engineering team’s insight into the system’s behavior strengthens its relationship with the customer. Outstanding customer service is a priority; beyond product design and development, Hatz engineers implement the engine integration in the customer’s work environment. Using Simcenter Amesim to model helps the engineers to predict the behavior of the engine and its parts in particular use cases. For example, they can predict how the designed cooling system will interfere with the main heat exchanger; how the interaction will affect the flow rates in the branches and, in turn, how that will affect issues such as oil temperature. As a result, they have a strong competitive advantage because they can tailor the engine to the customer’s specific needs.

Far beyond simple design tasks, Simcenter Amesim plays an important role in the Hatz product development process, leading to important savings of time and money.

“Simcenter Amesim interdisciplinary simulation software with its wide range of libraries – mechanical, thermal, hydraulics, electrical – lets us design our engines faster and more efficiently,” says Winter. “We can quickly assess and rank design variants. The model-based system engineering approach helps us tackle current and upcoming industry challenges.”