The dynamic solver considers fluid transport, convection and heat conduction within a fluid. To this end, every component inside the circuit carries a fluid volume. This approach enables transient thermal simulation of small and even zero mass flows. As the exemplary driving simulation shows, warm-up, cooling-down and converging of resting and low velocity fluids will be calculated precisely.
The example simulates cooling of an engine loaded by three, successive NEDC driving cycles demonstrating the beauty of transient simulations using KULI´s dynamic solver. The engine is lubricated and cooled by a closed oil circuit which is put into contact with a water/glycol circuit after a first warm-up. It considers the thermal inertia and thermal conductivity of fluid volume held by the components. Heat sources in the oil and the water/glycol circuit, respectively, model the rejected heat. Dummy tubes account for the fluid volumes held by the piping system of the engine.
A thermostat controls the coupling of the oil circuit with the water/glycol circuit via a parallel flow cooler. When its temperature is above 80 °C, it will open a confluence and heat will be exchanged. A second thermostat in the water/glycol circuit controls the coolant flow through the radiator. It keeps the respective branch shut until it reaches a temperature of about 90 °C. Then it begins to open which causes the high velocity, warm coolant in the bypass branch to be mixed with the resting, cold one from the radiator and its supply/discharge pipes. As a consequence the engine will experience a cold flush of coolant. The dynamic solver allows to simulate this phenomenon, calculating the transient thermofluidic properties of converging fluids of different temperatures and velocities. In addition to the already described components, the water/glycol circuit comprises further tubes, fluid resistances, a coolant pump and a heater. Featuring these components, the water/glycol circuit is modeled in a more detailed way than the oil circuit in contact with it.
Keywords: cold sip, temporal, time-critical, thermal mass, advection, point massUsable from release: KULI 13