Heat Transfer Analysis of a Radiator

Heat Transfer MEEN 3210

Dr. Li

Group Members

• Allison Sharrock• Bryon Kelling • Nevada Litterell• William Ray• Darren Hamel

History of a Radiator• In the 1880s, inventor Karl Benz

was designing and building "horseless carriages," the precursor to the early automobiles. Using simple internal combustion engines for power, these engines ran hot enough to boil off the water used to cool them at the rate of a gallon an hour. To solve this, Benz designed a system of coiled pipes through which engine-heated water would circulate and cool before returning to the engine to absorb more heat.Read

Parts of a Radiator

• Inlet- Connects to the Engine where hot water flows into the radiator tubes.

• Fins- Aluminum tubes pass through the fins. The fins draw heat from the water and transfers it to the air.

• Thermostat- Located on the engine, the thermostat regulates the amount of fluid flowing through the radiator.

• Outlet- Cool water flows out of the radiator to the engine.

How it Works

• A car’s radiator is a heat exchanger that draws heat from the engine and transfers it to the air.

• Hot fluid is drawn from the engine into the radiator which passes through a series of aluminum tubes.

• The tubes pass through aluminum fins which draw heat from the water and dissipates it to the air.

• As the water circulates through the radiator, the water cools and flows back through the engine to start the process again.

Air Flow Analysis

Radiator Air Flow With Car At Operating Temperature and Thermostat Open

   

Air Speed (m/s) Air Temperature (°C)  

5.2 43.1  

5.1 45.9  

5.4 44.3  

5.4 47.7  

   

Average Air Speed (m/s) 5.28  

Average Air Temp (°C) 45.25  

Radiator Flow Rate

Radiator Flow Rate Calculations

Volume Displaced(ml) Time (s)

3820 6.2

4120 6.2

3720 6

   

Average Volume Displaced 3886.67

Average Time 6.13

Formula’s & Calculation’s• Air Surface Area = (Total # of Air Passages)(2)(Fin Distance)(Fin Height)+(2)

(Fin Height)(Fin Width) = .86387 m2

• Coolant Surface Area = (Number Of Flow Tubes)(2)(Tube Height) Radiator Legnth)+(2)(Tube Width)(Radiator Legnth) = .74405 m2

• Hydraulic Diameter = ((4)(Legnth)(Thickness)) / ((2)(Thickness + Legnth)) = 22.3448• Reynolds # = ((Volumetric Flow Rate)(Hydraulic Diameter) / (Kinematic

Viscosity)(Crossectional Area)) = 3133.81 Which Is Transient Flow• Prandlt Number of Water =A low value means high convection= 1.96• Nusselt # = .23(Prandlt #).3(Reynolds #).8 = 176.304• Convection Heat Transfer Coefficient = ((Thermo conductivity)/(Diameter)

(Nusselt #)) = 172.149 w/m2k

Efficiency• Fin Efficiency = ηf = (tanh(mLc))/(mLc) = .0248

• Overall Surface Efficiency = ηo=1-(NAf/At)(1-Nf) = .024881 = 2.4 %

QUESTIONS?