What is Heat Recovery Efficiency

For supercritical CO2, a small change in temperature or pressure can result in large change in density, especially in the state close to the critical point. The large change in density can easily induce the natural convective flow. In this chapter, a solar water heater using supercritical CO2 which is originally designed and constructed will be introduced. The solar water heater is a closed loop system with main components of an evacuated solar collector and a heat exchanger. The working fluid of CO2 is naturally driven by the large change in density with absorbing and transporting heat in the solar collector. And the heat energy (hot water) is produced by exchanging the transferred heat with water in the heat exchanger. This chapter will describe the typical system operation and performance at different season and climates.