Question

Determine the minimum required coolant mass flow rate to avoid boiling using 50/50 Glycol properties

Understand the function of pressure cap. What does a pressure cap do in an automotive cooling system?

What is the construction of a pressure cap?

How does it perform its function? What are the possible failure modes? How likely are these failure modes? Are you familiar with FMEA's?

Choose a heat exchanger configuration - Parallel vs Counter flow

Think about fluid allocation. Which side the coolant should go and why?

Answer 1

2. The Function of pressure cap & its automobile cooling function will be discussed in later paragrah.

the engine’s coolant heats, it expands, increasing pressure inside the closed coolant system. The radiator cap controls this expansion and provides a constant pressure on the system. The caps pressure rating varies by engine application anywhere from 13 – 16 psi. High performance caps range from 19 – 32 psi. Water boils at 212° F, increasing the pressure in a closed system increases the boiling point. This allows manufacturers to manufacture engines with higher operating temperatures

The radiator cap also allows the engine’s coolant to expand and contract without all allowing air to enter the cooling system. The upper seal seals and protects the system at all times. After the engine warms and system pressure reaches the caps rated pressure, the pressure spring compresses and pressurized coolant flows into the reservoir or coolant overflow tank. This allows for expansion of the heated fluid.

The cap also allows the coolant to flow back into the radiator as the engine cools. The radiator cap also contains a vacuum valve. As temperatures drop and the coolant contracts a vacuum is created in the engine’s cooling system. The vacuum valve opens and allows coolant to flow from the overflow tank back into the radiator. This allows for contraction as the fluid cools.

3. Constrution of cap .