4. An ice skating rink is located in an indoor shopping mall with an environmental air temperature of 22°C, and radiation surrounding walls of about 25 °C. The convection heat transfer coefficient between the ice and air is about 10 W/m2 °C (because of air movement and the skater's motion). The emissivity of the ice is about 0.95. Calculate the cooling required to maintain the ice at 0°C for an ice rink having dimensions of 12 by 40 m. Obtain a value for the heat of fusion of ice and estimate how long it would take to melt 3 mm of ice from the surface of the rink, if no cooling is supplied and the surface is considered insulated on the back side.