Heating Performance Characteristics of High-Voltage PTC Heater for an Electric Vehicle

3/min and is controlled by 3700 W, 220 V inverters. The airflow was measured by a micro-manometer connected to a Pitot tube installed in the internal center of the air channel, and it was calculated according to the CIPM-81/91 regulations of the CIPM (International Committee for Weights and Measures) [

The experimental high-voltage PTC heater equipment, which was designed according to ASHRAE standards such as 37, 41.2, 51, contained as its main components an air channel system, environment chamber, DC power supply, and data acquisition system (DAQ). The equipment was designed to replicate the operating conditions and to gather data of the heating system in electric cars, as shown in Figure 2 16 ]. We measured the heating performance of the heater by installing temperature, humidity, and pressure sensors. Table 2 lists the specifications of all the experimental equipment. The air channel system and the environment chamber are connected to each other to create a closed loop. The environment chamber creates a section where the flow is stagnant to minimize the temperature deviation in the experimental part of the PTC heater. A suction type was applied to construct an air channel system, and a honeycomb-shaped distributor was installed to minimize maldistribution of the flow. The air speed deviation within the air channel is ±1.0% at 1.5 m/s, and the turbulence coefficient is ±1.0% at 1.5 m/s. The blower, which simulates the airflow conditions in the HVAC system of an electric car uses a centrifugal fan with a maximum volumetric flow of 5 m/min and is controlled by 3700 W, 220 V inverters. The airflow was measured by a micro-manometer connected to a Pitot tube installed in the internal center of the air channel, and it was calculated according to the CIPM-81/91 regulations of the CIPM (International Committee for Weights and Measures) [ 17 ]. The air pressure sensor for measuring the airflow had a measurement range of 600–1100 mb with a precision of ±0.25% at full scale (FS), and the temperature/humidity sensor had a temperature precision of ±0.25% at 0–50 °C, and a humidity measurement range of 0–100% with a precision of ±1.5% at 5–95% relative humidity. The temperature of the inlet flow and outlet flow passing through the PTC heater test section was measured with a K-type thermocouple with an error of ±0.1%. The front of this test section is fitted with six (array of 2 × 3) thermocouple meshes, whereas the rear contains 54 (array of 9 × 6) thermocouple meshes. The rear thermocouple mesh takes into account the radiant heat of the heat dissipation section, and it is located over 30 mm away from the heater surface at the output side of the heat dissipation section. The pressure drop was measured by recording the difference in pressure values measured at the four holes in the front and back of the heater test section. These holes were connected to the pressure sensors via tubes, and the pressure was measured as the average of the four holes. The measurement range of the pressure sensor was 0–124.42 Pa, and its accuracy was ±0.14% at full scale (FS). The power supply of the PTC heater is a 500 V/30 A high-voltage DC power supply, and it is measured and controlled using a computer via GPIB communication. A measurement program was created such that all of the data obtained as results in the experiments could be saved in the computer via a data logger and confirmed in real time.