Aspherical tank 2m diameter contains liquefied fuel gas. it is covered in insulation 120mm thick with a thermal conductivity of 0.025w/mk. the surface heat transfer coefficient between the lagging and the surrounding air is 30w/m2k. the air is at 25°c and the liquid is -125°c. assume the inner surface temperature is the same as the liquid. calculate the heat transfer rate required to keep the liquid at a constant temperature and surface temperature of the insulation.