In order to calculate heat transfer capacity and air-side pressure drop of an annular radiator (AR). one performance calculation method was proposed combining heat transfer unit (HTU) simulation and plate-and-fin heat exchanger (PFHX) performance calculation formulas. This method can obtain performance data with no need for meshing AR as a whole. which can be convenient and time-saving. https://lockdownsecuritycanada.shop/product-category/smartphone-controller/