A solar collector to convert CO2 to CO at high temperature was previously developed, achieving a product with 4-6 mol % CO from pure CO2. Modeling results showed that reactions occurred in the thermal boundary layer of the heated zirconia rod at temperatures greater than 2300 K. This paper describes results of computer modeling of advanced designs meant to increase the conversion of CO from CO2. Several design modifications were tested using the model, including changing the cool-down region configuration, increasing the zirconia rod diameter, and changing the zirconia rod shape. Several operational adjustments were also modeled, including reducing the flow rate, dilution of CO2 with helium, and increasing the prototype operating pressure. Modeling results predicted that all of the proposed design modifications improved the CO conversion. Increasing the operating pressure and decreasing the flow rate were beneficial, but dilution of CO2 with He was predicted to decrease the amount of product CO. Several design modifications and operational adjustments have already been implemented experimentally and have increased the conversion of CO from CO2.