) Average gas velocity = 1000 m/s
(e) Gaseous conductivity = 10 Mho/m

Section C Marks 10 each

7. (a) The following data are given for a family biogas digester suitable for the output of ten cows:
(i) The retention time is 25 days
(ii) Temperature = 30 oC.
(iii) Dry matter consumed per day = 3 kg.
(iv) Biogas yield = 0.34 m3 per kg.
(v) Burner efficiency = 60%.
(vi) Methane proportion = 0.8.
(vii) Heat of combustion of methane = 28 MJ/m3.

Calculate the volume of biogas digester and power available for it.

(b) Give a brief outline on application of solar energy in water refrigeration and air conditioning.

8. (a) for a thermoelectric power generator the following parameters are given:
Temperature of hot reservoir of source = 700 K
Figure of merit for the material z = 2 x 10 -3 K.

What will be the efficiency of the thermoelectric generation? What will be its cannot efficiency?

(b) Give the classification of fuel cells. Write their advantages and limitations.

9. Write short notes on any two of the following:
(a) Design of a community biogas plant.
(b) Tidal power potential in India
(c) Wind energy storage