In Problem 3.134, the prescribed value of ho = 1000 W/m2 ∙ K is large and characteristic of liquid cooling. In practice it would be far more preferable to use air cooling, for which a reasonable upper limit to the convection coefficient would be ho = 250 W/m2 ∙ K. Assess the effect of changes in the pin fin geometry on the chip heat rate if the remaining conditions of Problem 3.134, including a maximum allowable chip temperature of 75°C, remain in effect. Parametric variations that may be considered include the total number of pins, N, in the square array, the pin diameter Dp, and the pin length Lp. However, the product N l/2 Dp should not exceed 9 mm to ensure adequate air flow passage through the array. Recommend a design that enhances chip cooling.