A heat exchanger is configured to be arranged on a first housing of an electronic device, wherein the first housing has a top surface and a sidewall neighboring on the top surface, wherein the first housing has multiple first metal sheets protruding from the sidewall of the first housing. The heat exchanger includes a second housing configured to be mounted to the first housing, wherein a first opening is at a bottom of the second housing and configured to have the electronic device extend into an inner space in the second housing through the first opening, and a second opening is at a wall of the second housing and communicates with the inner space. The heat exchanger includes multiple second metal sheets in the inner space, wherein the second metal sheets are configured to be arranged over the top surface of the first housing, and a first heater in the inner space and thermally connected to the second metal sheets.