Heat and Mass Transfer in Food Processing

A stainless steel plate of a pasteurizer has thickness $x = 0.001\text{ m}$ and thermal conductivity $k = 16\text{ W/(m}\cdot\text{K)}$. The convective heat transfer coefficients on milk and hot water sides are $h_1 = 2000\text{ W/(m}^2\cdot\text{K)}$ and $h_2 = 4000\text{ W/(m}^2\cdot\text{K)}$, respectively. Neglecting fouling resistances, the thermal resistance $\sum R = \frac{1}{h_1} + \frac{x}{k} + \frac{1}{h_2} = 0.0005 + 0.0000625 + 0.00025 = 0.0008125\text{ m}^2\cdot\text{K/W}$. The overall heat transfer coefficient $U = 1 / \sum R$ in W/(m$^2\cdot$K) is: