Abstract
Abstract To study the internal flow characteristics of the photovoltaic pump under the transient change of solar radiation, the simulation algorithm of the photovoltaic pump system was established by MATLAB/Simulink and CFD for the first time and the results were validated by the test. Firstly, the change rule of pump flow rate and rotation speed under transient solar radiation was obtained by Simulink. Then the results of the change rule were transformed into the boundary condition of CFD by CEL function and the transient flow field in the photovoltaic pump was obtained. The internal flow characteristics and pressure pulsation in the pump were analyzed when the solar radiation increases or decreases transiently. The results demonstrate that the numerical calculation can provide accurate prediction for the characteristics of internal flow in the pump. The numerical results are closed to the experimental results, the minimum error of pressure is 0.93% and the maximum error is 1.78%. When the solar radiation increases transiently, the low pressure area at the impeller inlet gets larger obviously and the jet-wake at the impeller outlet becomes more obvious. The pressure pulsation in the impeller gradually increases and becomes stable after 0.6 s. The pressure from the impeller outlet to the guide vane outlet is stable at 123 kPa. When the solar radiation decreases transiently, the pressure in the impeller takes 1.6 s to be stable. Larger pressure pulsation occurs from the impeller outlet to the guide vane inlet and the maximum differential pressure is 10 kPa. Compared with the transient increase of solar radiation, the pressure in the impeller takes over 0.2 s to stabilize when the solar radiation transient decreases. Meanwhile, the results in this paper can provide references for other transient characteristics research.
Highlights
With the many advantages of energy saving, environmental protection, low cost and good adaptability to crops, photovoltaic pump systems are widely used in agricultural irrigation, urban waterscape and grassland animal husbandry, etc
There are many studies on optimization of photovoltaic pump systems, most of the research focus on maximum power point tracking (MPPT) (Sun et al 2013; Suo 2017; Xing 2017), motor control (Moulay-Idriss & Mohamed 2013; Mapurunga et al 2014; Zhen & Zhen 2017) and system matching (Benghanem et al 2013; Liu 2017; Liu et al 2017), little attention was paid to the photovoltaic pump performance under transient solar radiation, which is very important to the photovoltaic pump design
When the solar radiation increases transiently, the static pressure at the impeller outlet increases obviously and the flow becomes steady after t 1⁄4 1.0tc
Summary
With the many advantages of energy saving, environmental protection, low cost and good adaptability to crops, photovoltaic pump systems are widely used in agricultural irrigation, urban waterscape and grassland animal husbandry, etc. There are many studies on optimization of photovoltaic pump systems, most of the research focus on MPPT (Sun et al 2013; Suo 2017; Xing 2017), motor control (Moulay-Idriss & Mohamed 2013; Mapurunga et al 2014; Zhen & Zhen 2017) and system matching (Benghanem et al 2013; Liu 2017; Liu et al 2017), little attention was paid to the photovoltaic pump performance under transient solar radiation, which is very important to the photovoltaic pump design. As for the photovoltaic pumps, the transient solar radiation leads to change of the pump rotational speed and flow rate, which makes it difficult to give boundary conditions for internal flow simulation of the photovoltaic pumps To solve this problem, the dynamic characteristic algorithm of the photovoltaic pump system was established by MATLAB/Simulink. Based on the analysis of the internal flow in the photovoltaic pump, the optimization method and design method for the photovoltaic pump can be explored, which can make the photovoltaic pump more high efficiency and stable under variation of conditions
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