There are different ways to expel the heat. Many of the amateur cameras available today expel the heat by convection to the atmosphere, or ambient air. The CCD camera has fins on the backside of the body that helps this convection. With this type of cooling there is a maximum difference produced between the ambient and the amount the chip can be cooled. The chip temp will always be a function of the ambient temperature.
Most professional camera use liquid nitrogen in a chamber on the camera.
At this temperature it is necessary to heat the chip with heating resistor to avoid damage. Other cameras have an external cooling source. A coolant is pumped past the peltier and carried out to an external cooler. The cookbook camera has this type cooler. These type coolers are not limited to expelling heat to the air and we can control the CCD temperature by controlling the temperature of the coolant.