Cooling System Case Study

Figure 4.1 –Indication of various points in the diagram

Figure 4.1 shows the schematic diagram of a cooling system with numbering at each point throughout the system to indicate where the temperatures and pressures vary, heat loads and flow varies with respect to the speed of the engine. It is not a model just a assumption that cooling system contains minimum apparatus to run. So, through these assumptions a program was developed to evaluate the operating values of cooling system of any design.

1 P¬2 = P1 – ρg[(K12(ṁ/ρA12)2/2g) – Z1 + Z2]

2 P3 = Pamb + ρgZsurge

3 P¬4 = P3 – ρg[(K34(ṁ/ρA34)2/2g) – Z3 + Z4]

4 P5 = P4 + ρgHpump

5 P¬6 = P5 – ρg[(K56(ṁ/ρA56)2/2g) – Z5 + Z6]

6 P¬7 = P6 – ρg[(K67(ṁ/ρA12)2/2g) – Z6 + Z7]

7 P¬6a = P6 – ρg[(K66a(ṁrec/ρA66a)2/2g)

The developed temperature model in Kelvins is [19]:

T= 302 + 8sin (0.00436t - 2.3)

This equation was developed by assuming the maximum daily temperature to be 310 K, the minimum temperature to be 294 K, and the time of day, t, is in minutes. The cooling system allows the user to know the daily temperature range. Using this equation in the MATLAB enables the user to identify how the cooling system responds to changes in the ambient temperature in a whole day.

4.4 Cooling System Computer Model

The previously derived equations were coded in the MATLAB program. Figure 4.4 represents a flow diagram of the cooling system computer model. The cooling system model is broken down into the following steps:

1. The user provides the inputs.

2. Friction factors and pressure loss coefficients at finfan unit and oil cooler were calculated through the equations (20) and (24).

3. The energy added to the cooling system from in-cylinder of the engine, is calculated using Equations (17), (20), (21) and (31) from equations