kibl77
Mechanical
- Sep 6, 2010
- 1
Hi, I need to size a CHP system to make sure it covers for the heat load of an anaerobic digester AD and 1,075 litres of water at 81 C at worse conditions; i.e. lower mass flow rate from CHP (at specified thermal output 45kw will be with low inlet water CHp) (water inlet CHP 4 Celcius, chp output thermal 45kW and Tout CHP 81 C; slurry Cp 4.05 volume 14350 kg/day or 0.166kg/s, T AD 37 and T slurry 0) I have calculated the mass flow rate from the CHP to be 0.14 kg and the q for the feedstock 30 kW)
Now I am stuck, I don't know what to compare to determine that the output from the CHP is enough to cover the 34kW; can i compare the 30kW with 25kW obtained from 0.14*4.187*(81-37)=25kW. in this case it won't be enough. I was thinking to assume a close circuit to return the water to the CHP after the AD. this will give a higher Tinlet to chp (i don't know how to calculate the drop in temperature of water when it leaves the AD) and therefore a higher mass flow rate which will provide more than 25kW.
Please help, i tried to explain as good as i could.
Now I am stuck, I don't know what to compare to determine that the output from the CHP is enough to cover the 34kW; can i compare the 30kW with 25kW obtained from 0.14*4.187*(81-37)=25kW. in this case it won't be enough. I was thinking to assume a close circuit to return the water to the CHP after the AD. this will give a higher Tinlet to chp (i don't know how to calculate the drop in temperature of water when it leaves the AD) and therefore a higher mass flow rate which will provide more than 25kW.
Please help, i tried to explain as good as i could.