No abstract

This paper derives a new integral relationship between heat flux and temperature in a transient, two-dimensional heat conducting half space. A unified mathematical treatment is proposed that is extendable to higher-dimensional and finite-region geometries. The analytic expression provides the local heat flux perpendicular to the front surface solely based on an embedded line of temperature sensors parallel to the surface. The relationship does not require apriori knowledge of the surface boundary condition. A new sensor strategy is analytically conceived based on the integral relationship for estimating the local, in-depth heat flux without surface instrumentation. It should further be clarified that the integral relationship requires only knowledge of the local, in-depth temperature and heating/cooling rate (time rate of change of temperature). The resulting formulation is mildly ill-posed and either requires digital filtering of the temperature signal to remove high frequency components of noise or the development of direct heating/cooling rate sensors. This paper (a) develops the new mathematical relationship; (b) demonstrates that the proposed relationship reduces to well-known (i) one-dimensional results under the appropriate assumptions; and, (ii) two-dimensional surface results; and, (c) provides a simple numerical example validating the concept.

No abstract

The purpose of this study is to determine the thermal feasibility of an air-cooled 55-kW power inverter with SiC devices. Air flow rate, ambient air temperature, voltage, and device switching frequency were studied parametrically by performing transient and steady-state simulations. The transient simulations were based on inverter current that represents the US06 supplemental federal test procedure from the US EPA. The results demonstrate the thermal feasibility of using air to cool a cylindrical-shaped 55-kW SiC traction drive inverter with axial-flow of air. When the inverter model is subject to one or multiple current cycles, the maximum device temperature does not exceed 164°C (327°F) for an inlet flow rate of 270 cfm, ambient temperature of 120°C, voltage of 650 V, and switching frequency of 20 kHz. The results show that the ideal blower power input for the entire inverter with a total inlet air flow rate of 540 cfm is 312 W.

Fig. 1, m ρ = density, kg/m 3