Coolant Piping System Research Paper

3.4 Coolant Piping System

The cooling water piping system was modelled by applying fluid dynamic principles.

Figure 3.4 – Schematic of system

3.4.1 Coolant Piping, Fittings, Valves, and Surge Tank

The resulting pressures are determined by using the modified Bernoulli’s equation, Equation (16).
The dimensionless factors are used to determine the head losses within the piping system. The dimensionless friction factors used to develop the model, for 90 degree bends, 45 degree bends, valves, and the TCV are shown in Table 3.1.

Table 3.2 – Dimensionless Friction Factors

K90 K45 Kvalve KTCV 0.2 0.14 6.0 8.0

Along with the fitting friction factors, the friction factor due to the pipe roughness must be considered. The

As the engine speed varies, the pump speed varies RPMp, and it is a function of the engine speed, RPMeng. There is a linear relation between the engine and pump speeds, then pump speed is calculated by:
RPMp = (RPMp, known/ RPMeng, known) RPMeng ------------------- (23)

Once the pump speed is determined, the pump affinity laws are used to calculate the pump head and coolant flow rate.
The cooling equipment includes the engine, fin-fan unit, and the oil cooler for system. The OEM operating guidelines provide a maximum value for the pressure losses across the cooling equipment. The following equation is derived to calculate the differential pressure across the cooling system. Since, the pressure differential is the function of mass flow rate then the derived equation is:
∆P = Ktotal ((ṁ/ρA) 2)/2) ρ = βṁ2 --------------------- (24)
Where,
β = pressure loss coefficient K = friction factor

This equation represents the pressure loss through a given component is a function of coolant mass flow rate for a given cooling system