Design and Commissioning of a Thermal Radiation Chamber with Design Confirmation via Finite Element Model

Abstract

Research into low heat transfer internal combustion engine technology has led to a need for new testing devices that can generate heat flux at levels similar to those found in a Homogeneous Charge Compression Ignition engine (~1.0 MW/m2) but isolated from the reciprocal pressure environment. A Thermal Radiation Chamber was developed to accommodate this need. This system uses a graphite resistive heating element to generate resistive joule heating. The heat flux is measured via custom, high speed heat flux sensors made by IR Telemetrics of the same construction utilized in numerous internal combustion engine research studies. A stainless steel wheel, featuring two cut-outs and cooled by internal water channels, rotates between the graphite heating element and the custom probes to mimic the required periodicity of the heating events. A finite element simulation was created to predict the response of the heat flux sensors so that the requisite distance between the graphite element and the custom heat flux sensors could be predicted such that the probes, even if coated with an insulative substance, would still register temperature swings beyond their measurement uncertainty (~1.1°C or 0.4% of full scale). Informed by the finite element solution, the radiation chamber design was finalized, and the device was constructed and commissioned. Subsequently, several experimental trials were conducted to validate the finite element model predictions. The Thermal Radiation Chamber exceeded its design requirements, generating over 2.0 MW/m2 and temperature swings observed to exceed 15°C. The simulation accurately predicted the shape of the response of the heat flux sensors. With small modifications, the model was brought into quantitative agreement with the experimental data and now stands ready for further application in designing insulative coatings for low heat rejection internal combustion engines.