This article proposes a dual heat source heat pump bathroom unit with preheater which is feasible for a single family. The system effectively integrates the air source heat pump (ASHP) and wastewater source heat pump (WSHP) technologies, and incorporates a preheater to recover shower wastewater heat and thus improve the total coefficient of performance (COP) of the system, and it has no electric auxiliary heating device, which is favorable to improve the security of the system operation. The process simulation software ASPEN PLUS, widely used in the design and optimization of thermodynamic systems, was used to simulate various cases of system use and to analyze the impact of the preheater on the system. The average COP value of a system with preheater is 6.588 and without preheater it is 4.677. Based on the optimization and analysis, under the standard conditions of air at 25 °C, relative humidity of 70%, wastewater at 35 °C, wastewater flow rate of 0.07 kg/s, tap water at 15 °C, and condenser outlet water temperature at 50 °C, the theoretical COP of the system can reach 9.784 at an evaporating temperature of 14.96 °C, condensing temperature of 48.74 °C, and preheated water temperature of 27.19 °C.

In certain industries, such as the Chinese pharmaceutical pill preparation medicines, the occurrence of satellite droplets and the inconsistent diameters of the main droplets lead to wasted resources and affect the normal operation of the production system. So it is necessary to investigate the formation process of main droplets and the elimination method of satellite droplets in the jet process. In this paper, the effects of the liquid level height, dropper inner diameter, and glycerin mass fraction on the formation of the droplets are revealed, and the optimal frequency for eliminating satellite droplets is explored. The results show that the diameter of the main droplets increases as the liquid level height and the dropper inner diameter increase and decreases as the glycerin mass fraction increases. The fracture length has a growing trend as the liquid level, dropper inner diameter, and glycerin mass fraction increase. With the increase in the dropper inner diameter and glycerin mass fraction, the generation period increases. However, the increase in the liquid level height has an opposite influence on the other parameters. The optimal frequency for eliminating satellite droplets increases as the liquid level height and dropper inner diameter increase and decreases as the liquid becomes more viscous. However, the diameter and generation period of the main droplets decrease when a longitudinal disturbance is added to the jet system.