Available online at www.sciencedirect.com
ScienceDirect Energy Procedia 88 (2016) 574 – 580
CUE2015-Applied Energy Symposium and Summit 2015: Low carbon cities and urban energy systems
Energy Optimization by Parameter Matching for a TruckMounted Concrete Pump Ye Mina*, Yi Xiaogangb, Jiao Shengjiea National Engineering Laboratory for Highway Maintenance Equipment, Chang’an University, Xi’an, 710064,China SANY Heavy Industry Co. Ltd. Research and Development Institute, Changsha, 410100,China
Abstract Aiming at the shortages of low efficiency and large fuel consume of a truck-mounted concrete pump, a global power matching method are proposed based on both fuel consume rate of the engine and efficiency of the hydraulic pump. The combination optimization on fuel consume rate of the engine and efficiency of the hydraulic pump are realized by genetic algorithm. The control objects, as far as the rotating velocity of the engine and the displacement of the hydraulic pump, can be adjusted at the same time and follow with the load adaptively, resulting in that all the components working at high efficiency region. The comparative experiments are tested with the new and old methods. The results showed that the new one was superior to the old. The average energy save ratio is 16%. © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license © 2015 The Authors. Published by Elsevier Ltd. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Selection and/or peer-review under responsibility of CUE Peer-review under responsibility of the organizing committee of CUE 2015
Key wors: fluid power and control, power matching, energy economy, efficiency
Nomenclature Q
the pump flow
P
the pump pressure
n
the pump velocity
q
the pump displacement
* Corresponding author. Tel.: +0862982334487; fax: +0862982334869. E-mail address:
[email protected].
1876-6102 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of CUE 2015 doi:10.1016/j.egypro.2016.06.080
Ye Min et al. / Energy Procedia 88 (2016) 574 – 580
1. Introduction With ever increasing concerns on the energy diversification and environmental protection, the energy conservation technology has been widely used in automobile industry, such as a hybrid electric vehicle[1]. As we know, the power of a truck-mounted concrete pump is at least twice more than that an automobile, for instance the engine power of a truck-mounted concrete pump is 214kW and that the power of a Toyota Prius is only 73kW[2]. So the energy conservation technology is much more important than an automobile. The hydraulic system of a concrete pump is a typical open-loop system, as shown in figure 1(a). Because that the fuel consume of a truck-mounted concrete pump are variable with different load(figure 1(b)), the optimal control for the engine output power can realize the objective of energy conservation. The hydraulic system consists of the engine, the main pump and the hydraulic cylinders. Field test found the hydraulic shock of the main pumping outlet is serious, and heard great sound of the piston striking the bottom of the cylinder. When the pumping load varies in the range of 0MPa to 20MPa, the piston stroke decreases with the increase of the variation of the pumping load, and leads to the pumping insufficiency. Therefore, the mismatch between varying loads and system’s open-loop control property can leads to the problem of pumping insufficiency[3]. Therefore, in order to solve foresaid problem, the optimal model of concrete pumping displacement control must be built to find the best set of control parameters which is suitable for a wide range of dynamic load.
(a) The Schematic diagram
(b) The load vibration characteristics Figure 1 The outline of a truck-mounted concrete pump
575
576
Ye Min et al. / Energy Procedia 88 (2016) 574 – 580
2. The energy conservation strategy The universal characteristics curve of an engine is shown in figure 2, where the horizontal coordinate ne is the engine speed, the longitudinal coordinate Te is the torque, Ne is the constant power contour (the dashed lines), and the thick solid line is the fuel consumption ratio ge. When the load requirement power is 60kW, there are at least three working points for the engine, such as the “star mark”, “triangle mark” and “circle mark”. However, for both the “circle mark” and the “triangle mark”, the fuel consume ratio are 260g/kW.h, for the “star mark”, the fuel consume ratio is only 240g/kW.h. It will save 20g fuel if the engine works at the “star mark” for an hour than that works at other points. If we connect all the “star mark” under different power requirement, we can get the lowest fuel consume ratio of the engine, namely the best economical fuel consumption curve(S curve in figure 2).
Figure 2 The universal characteristics of an engine The energy conservation strategy of a truck-mounted concrete pump is as follows: study the character curve of engine to find out the best economical fuel consumption curve (S curve in figure 2) and then arrange the work point of the engine to be near the curve according to the truck working conditions. Take advantages of the hydraulic transmission system of good controllability, continuous adjustment and reasonably matching different parameters to meet the operating requirements of the truck to achieve the energy conservation target. 3. The global power matching by genetic algorithm Aiming at the shortages of low efficiency and large fuel consume of a truck-mounted concrete pump, a global power matching method are proposed based on both fuel consume rate of the engine and efficiency of the hydraulic pump. The combination optimization on fuel consume rate of the engine and efficiency of the hydraulic pump are realized by genetic algorithm. The control objects, as far as the rotating velocity of the engine and the displacement of the hydraulic pump, can be adjusted at the same time and follow with the load adaptively, resulting in that all the components working at high efficiency region. The energy saving principle is shown in figure3. The efficiency of both the engine and the hydraulic pump is tested firstly. Then the optimal engine velocity and the pump displacement are outputted. It can be seen from figure 3 that the corresponding engine speeds on the lowest operating point under different
577
Ye Min et al. / Energy Procedia 88 (2016) 574 – 580
powers differs from each other. The engine is controlled to output the power to match different working conditions by adjusting the engine speed. min( g e / Ob )
^
ge (ne ,Te ) Ob (nb , Pb , qb )
^
ne
qb
Figure 3 Schematic of global power match The input is the required flow Q and the pump pressure P to propel the concrete at given velocity. The q output is the engine velocity n and the pump displacement . At the given load condition ( Pi , Qi ) , the ( n , q ) i i control system optimizes the parameters ˈwhich can ensure the minimum energy loss for the power transmission system. The optimal object is shown in equation (1). min gp( n,P q ) g e (T , n) / O p ( n, p , q ) ˄1˅ i ° .t. ®nthe * q subject sAnd Qi condition for the global economic model is shown in equation (2). °T p * q /(2S ) ¯ ˄2˅
4. Experiments
The fuel consume rate of the engine is tested on the engine test plat. It can be seen from figure 4, that the engine’s efficiency is high within the velocity region [850rmp 1400rpm], and the torque region [800N.m 1300N.m].
Figure 4 The fuel consumption curve of the engine (unit: g/kW•h)
Secondly, the experiments are carried out on the hydraulic pump to find out the high efficiency region with different pressure, rotating velocity and displacement, which are shown in figure 5. The efficiency of
578
Ye Min et al. / Energy Procedia 88 (2016) 574 – 580
the pump is high within the region of pressure [10MPa 20MPa] and the velocity region [1000rpm 1300rpm].
Figure 5 The efficiency of the hydraulic pump (unit: %)
The displacement control parameters after optimization can solve the problem of mismatch between varying loads and system’s open-loop control property. So the experiments are carried out to compare the fuel consumptions. Finally the energy-saving effect is calculated by the specific fuel consumption of the prototype in each power point with the proposed control method and the old control method. For the old method, the engine velocity is adjusted to the rated value 1850rpm. It is not rational from figure 4, because the 1850rpm is located outside the economic region. From figure 6, it can be concluded that the working points Locate outside the contour curve 210 g/kW•h, which is shown in figure 6(a). however the ratio decreased to 15%ˈfor the new control method. After calculation it can be concluded that the average energy saving ratio is 15% for the proposed control method than the old one.
(a) The old control method (unit: g/kW•h)
Ye Min et al. / Energy Procedia 88 (2016) 574 – 580
(b) The proposed control method (unit: g/kW•h) Figure 6 The torque and velocity distribution under different control methods
The experiments validate the effectiveness of the energy conservation of the proposed method. The methodology can be widely used in the heavy construction machinery, such as the paver, the wheel loader and rollers. It can conserve the fuel and lessen the environmental pollution, furthermore accelerate the sustainable economic development. 5. Conclusion
Aiming at the environmental protection and energy diversification, this paper studies the features of the drive line of a truck-mounted concrete pump and proposes an energy conservation strategy. The engine’s efficiency is high within the velocity region [850rmp 1400rpm], and the torque region [800N.m 1300N.m]. The efficiency of the pump is high within the region of pressure [10MPa 20MPa] and the velocity region [1000rpm 1300rpm]. Results of experiments show that the energy-saving effect is obvious by this technology and 15% of fuel can be saved. 6. Copyright
Authors keep full copyright over papers published in Energy Procedia Acknowledgements
The authors gratefully acknowledge support from the Special Fund of Basic Research Support Program of Chang’an University (Grant No CHD2011ZD017). References [1] C. Morton, V. Pickert, and M. Armstrong(2014). Self-alignment torque as a source of energy recovery for hybrid electric trucks. IEEE Transactions on Vehicular Technology, vol. 63, pp. 62-71. [2] T. Wang and Q. Wang(2014). Efficiency analysis and evaluation of energy-saving pressure-compensated circuit for hybrid hydraulic excavator. Automation in Construction, vol. 47, pp. 62-68.
579
580
Ye Min et al. / Energy Procedia 88 (2016) 574 – 580
[3] X. Zeng, N. Yang, Y. Peng, and Y. Zhang(2014). Research on energy saving control strategy of parallel hybrid loader. Automation in Construction, vol. 38, pp. 100-108.
Biography
Min Ye is a professor from Chang’an University. He got his Ph.D from Xi’an Jiaotong University. His interests are the energy saving technology of electric and hybrid vehicles, which include the application for the construction machinery.
