Performance analysis of temperature-dependent near-field thermophotovoltaics with passive radiative cooling approach

Radiative cooling (RC) has emerged as an effective method for dissipating excess heat in energy conversion technologies, such as thermophotovoltaic (TPV), through mid-infrared radiation into the clear sky, which is crucial for improving energy efficiency and supporting carbon reduction efforts. However, the lower temperatures of TPV systems result in limited power density. To address this challenge, the concept of near-field thermophotovoltaics (NTPV) has been introduced, which harnesses near-field effects to enhance performance. Here, a temperature-dependent model of an NTPV system is established, incorporating a calcite emitter, an InSb cell, and a RC module, while accounting for the temperature-dependent bandgap energy and permittivity of the cell. The performance of the proposed system is analyzed by comparing with the other two configurations. Due to the availability of more photons above the bandgap, the proposed system achieves 954.49 W/m2 power density and 44.63 % efficiency when emitter is 600 K and gap is 20 nm, representing a 109.3 % improvement over conventional NTPV. Additionally, the effects of the convective-heat-transfer coefficient, the area ratio between the RC module and the cell, and the selective and broadband RCs on the performance of the proposed system are analyzed.