Question

In the mixing device the slurry (mixture) of ice and water at temperature 0°C is mixed with water at temperature 20 C. The flow rate of the slurry (water + ice) is 2 kg/s and flow rate of the warm water is 4 kg/s. (a) Determine the mass flow rate of the ice, if the outlet temperature is 1°C and system is perfectly insulated. (b) Determine entropy generation rate in the perfectly insulated system. Specific heat of water is 4.19 kl/(kgK), latent heat of melting of ice is 333 kJ/kg. The steady state process is considered. The reference temperature is 273.15 K

Answer 1

Given that: - In the mixing device the slurry (mixture) System is perfectly insulated hence heat therefore transfer will occur Between mixture and wader heat given by water = heat accept by mix final temperature = 1 degrees C heat Given by water a = m_w^0 times CP_w times (T_f - T_i) = 4 times 4 times 19 x (1 - 20) = -318.44 kJ/m (pre indication had if regretted) Q_1 = 318.44 watt This heat will firstly meet the ice of mixture. Mean flow rate of ice = m_ice^0 Heat Required to meet ice of mixture = m_ice^0 times talent heat Q_1 = 333 m_ice^0 kJ/n Now remaining heat will increase the temperature of mixture to 1 degrees C Q - Q_1 = 2 times 4.19 = 8.38 kJ/n 318.44 - 333 m_ice^0 = 8.38 kJ/m a) therefore m_ice^0 = 0.9311 kJ/n Entropy Generation rate delta s_gen^0 = n_w^0 C_p (I_n (T^2/T_1) + m_mix^0 C_p in (T_2/T_1) + m_ice^0