Flow Rate Required to Spray Cool Sintered Material 1

[dspaz]

Hello Everyone,

I currently have an application where I need to cool sintered material on a conveyor by spraying water onto it. I would like to reduce the temperature from 650 to 100 degrees celcius. What I need to know is what information is needed to find out the flow rate of water required to satisfy this temperature change, and hence the equations that I need to solve.

Thanks a lot in advance.

 

[fegenbush]

The simple answer is to use the specific heat (kJ/kg*K) of the sintered material and its flow rate (kg/s)in combination with your required temperature change (650-100=550°C=550K) to determine the kJ/s (kW) that you require. Take the temperature of the water input (say 20°C), the boiling point of water (100°C), the specific heat of water (4.219 kJ/kg*K) and the latent heat of vaporization of water (2258 kJ/kg) and perform an energy balance to determine the water mass flow rate (kg/s). Use the density to determine the volumetric flow rate if you so require.

Vaporization in this way is fairly efficient, if you have good nozzle placement, but you should increase the flow from ideal to compensate for any effects of your mist cooling the air above the product instead of the product itself.

I hope this has been helpful to you.

 

[dspaz]

Thanks. The information I have so far is the thermal conductivity of the material (7.81 wmk) and that 60 tonnes is being produced per hour in lumps of up to 75 mm. Is there anyway I can use this info? What else would I need to obtain?

 

[fegenbush]

Since the minimum temperature of the sintered material is still at or above the boiling point of the cooling liquid, it is unlikely that you will require find the thermal conductivity particularly useful unless you want to conduct a transient analysis of the cooling of a 75 mm diameter lump. The only value that you do not have that is required is the specific heat capacity of the material. If you would inform us as to the composition of the material, perhaps someone on here has a value which you could use.