Between R4 as positive feedback and an undefined V2, I don't know what to make of this. The way I did it, R4 doesn't exist. Depending on accuracy required, you might need the chart for the thermistor. Use that to make a look-up table, or a linearizing circuit as per the thermistor manufacturer. Your U2 (without R4) is a simple gain of 2 followed by a 0.05 second time constant and a buffer amplifier.