Design of active and passive dual modes refrigerated container and analysis of environmental characteristics in the container

ObjectiveImproved cold chain transportation equipment and analyzed the impact of active and passive dual modes on the environmental distribution characteristics inside cold chain containers.MethodsAn active and passive dual-mode refrigerated container (temperature control range is -1~10 ℃) was proposed, which integrated refrigeration unit, fiber air supply pipe and phase-change cold storage plate. The system operated in passive cooling mode, and switched to active cooling mode when the air temperature inside the box was greater than 10 ℃.ResultsThe results showed that the velocity distribution in the active and passive dual mode box was uniform, and the air flow could reach all parts of the box. The temperature distribution in the active release mode was uniform, the temperature gradient in the box was small, and the maximum temperature difference was only 0.3 ℃. The temperature gradient in the passive release mode was slightly larger and the temperature non-uniformity was higher than the active release mode. Compared with the passive refrigeration mode alone, the active and passive dual mode could effectively ensure the long-term transportation of the temperature zone below 10 ℃, which was conducive to the refrigerated transportation of most fresh goods.ConclusionThe design of active and passive dual-mode cold chain container has great potential for energy optimization, uniform flow field, stable temperature and strong practical value.