| 摘要 |
PURPOSE:To enable to prevent reduction in performance from occurring at the time of frosting or dewing, by a construction wherein heat-radiating fins for an exterior-side heat exchanger are divided, and the shape of the second fins using internally grooved pipes is so set that the thermal conductivity on the air side of the fins is higher than that of the first fins using internally smooth pipes. CONSTITUTION:Where the outside air temperature is extremely low, frost 11b is adhered to the first fins 6a on the upstream side of air flow. However, since the first fins 6a consist of flat form fins having a small air flow resistance, reduction in air quantity is small, and air passes sufficiently therethrough, so that sufficient heat exchange is achieved on the side of the second fins 6b using the internally grooved pipes. Accordingly, reduction in temperature of the heat exchanger due to frosting is small, frost does not grow into ice, and a heating operation can be conducted with high efficiency. In addition, since fins ensuring a favorable water flow are used as the first fins, the period of time required for defrosting (removing the dew 11a) is shortened, and heating efficiency is enhanced. Accordingly, performance of the heating operation can be enhanced, and the cost can be reduced. |
