Consider a counter-flow heat exchanger with the inlet temperatures of two fluids (1 and 2) being T₁, in = 300 K and T₂, _in = 350 K. The heat capacity rates of the two fluids are C₁= 1000 W/K and C₂ = 400 W/K, and the effectiveness of the heat exchanger is 0.5. The actual heat transfer rate is _____ kW. (Answer in integer)