Design and evaluation of a refractance window lab-scale dryer

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shaffic Ssenyimba ◽  
Julia Kigozi ◽  
Peter Tumutegyereize ◽  
John H. Muyonga ◽  
Raymonds Mutumba

Purpose Refractance window drying (RWD) has been identified as the method that can give high-quality products at a relatively low production cost. However, knowledge about its use and adoption remains lacking both in academic curricula and industry in the developing world. Design/methodology/approach A lab-scale batch RWD of a closed-loop control system was designed, fabricated and evaluated for drying rates, evaporation rate, the energy of evaporation, energy efficiency and throughput. Testing was done using mango and tomato pulps. Findings Drying rates at 95°C of 1.32 gg−1min−1 and 0.854 gg−1min−1 at 2 and 3 mm, respectively, for tomato, 0.6 gg−1min−1 and 0.33 gg−1min−1 at 2 and 3 mm for mango pulp were obtained. The dryer had an evaporation rate of 4.63 × 10–4 kg/s and 4.25 × 10–4 kg/s, the energy of evaporation of 1.05 kW and 0.96 kW and thermal energy efficiency of 25.64% and 21.73% while drying tomato and mango pulps, respectively. Dryer throughput of 0.6 kg/h of dried mango Pulp and 0.47 kg/h of dried tomato pulp was obtained. Originality/value The designed RWD can be adequately used in laboratory experiments on different products to produce powders. This will enable the transfer of knowledge about RWD technology in developing countries.

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shangyong Tang ◽  
Guilan Wang ◽  
Hao Song ◽  
Runsheng Li ◽  
Haiou Zhang

Purpose Modeling and control of bead geometry in wire and arc additive manufacturing is significant as it affects the whole manufacturing process. The purpose of this paper is to establish an efficient model to control the bead geometry with fewer experiments in wire and arc additive manufacturing (WAAM). Design/methodology/approach A multi-sensor system is established to monitor the process parameters and measure the bead geometry information. A dynamic parameters experimental method is proposed for rapid modeling without dozens of experiments. A deep learning method is used for bead modeling and control. To adaptively control the bead geometry in real-time, a closed-loop control system was developed based on the bead model and in situ monitoring. Findings A series of experiments were conducted to train, test and verify the feasibility of the method and system, and the results showed that the proposed method can build the bead model rapidly with high precision, and the closed-loop system can control the forming geometry adaptively. Originality/value The proposed modeling method is novel as the experiment number is reduced. The dynamic parameters experimental method is effective with high precision. The closed-loop control system can control the bead geometry in real-time. The forming accuracy is elevated.


2019 ◽  
Vol 91 (7) ◽  
pp. 1002-1010
Author(s):  
Zilai Zhang ◽  
Shusheng Zang ◽  
Bing Ge

PurposeThis paper aims to develop a dynamic performance model of three-shaft gas turbine for electricity generation and to study a multi-loop control strategy of three-shaft gas turbine for electricity generation.Design/methodology/approachIn this paper, the dynamic performance model of the three-shaft gas turbine is established and developed. A novel approach, variable partial differential coefficient deviation linearization method is used to simulate the dynamic performance of the three-shaft gas turbine. Single-loop control system, feed-forward feedback control system and cascade system are assessed to control the engine during transient operation.FindingsA novel approach, variable partial differential coefficient deviation linearization method is used to simulate the dynamic performance of the three-shaft gas turbine. According to the results shown, the cascade control system is most satisfactory due to its fastest response and the best stability and robustness.Originality/valueThe method of variable partial linearization is adopted to make the dynamic simulation of the model achieve higher precision, better steady state and less computation time. This paper provides a theoretical study for the multi-loop control system of a marine three-shaft gas turbine.


2016 ◽  
Vol 4 (2) ◽  
pp. 1-16
Author(s):  
Ahmed S. Khusheef

 A quadrotor is a four-rotor aircraft capable of vertical take-off and landing, hovering, forward flight, and having great maneuverability. Its platform can be made in a small size make it convenient for indoor applications as well as for outdoor uses. In model there are four input forces that are essentially the thrust provided by each propeller attached to each motor with a fixed angle. The quadrotor is basically considered an unstable system because of the aerodynamic effects; consequently, a close-loop control system is required to achieve stability and autonomy. Such system must enable the quadrotor to reach the desired attitude as fast as possible without any steady state error. In this paper, an optimal controller is designed based on a Proportional Integral Derivative (PID) control method to obtain stability in flying the quadrotor. The dynamic model of this vehicle will be also explained by using Euler-Newton method. The mechanical design was performed along with the design of the controlling algorithm. Matlab Simulink was used to test and analyze the performance of the proposed control strategy. The experimental results on the quadrotor demonstrated the effectiveness of the methodology used.


2016 ◽  
Vol 10 (1) ◽  
pp. 99-117 ◽  
Author(s):  
Alberto De Marco ◽  
Giulio Mangano ◽  
Fania Valeria Michelucci ◽  
Giovanni Zenezini

Purpose – The purpose of this paper is to suggest the usage of the project finance (PF) scheme as a suitable mechanism to fund energy efficiency projects at the urban scale and present its advantages and adoption barriers. Design/methodology/approach – A case study is developed to renew the traffic lighting system of an Italian town via replacement of the old lamps with new light-emitting diode (LED) technology. Several partners are involved in the case project to construct a viable PF arrangement. Findings – The case study presents the viability of the proposed PF scheme that provides for acceptable financial returns and bankability. However, it also shows that the need for short concession periods may call for a public contribution to the initial funding to make the project more attractive to private investors. Practical implications – This case study is a useful guideline for governments and promoters to using the PF arrangement to fund energy efficiency investments in urban settings. It helps designing an appropriate PF scheme and understanding the advantages of PF to reduce risk and, consequently, increase the debt leverage and profitability of energy efficiency projects. Originality/value – This paper contributes to bridging the gap about the lack of works addressing the implementation of the PF mechanism in the energy efficiency sector in urban areas. The importance of this paper is also associated with the shortage of traditional public finance faced by many cities that forces to seek for alternate forms of financing.


Proceedings ◽  
2020 ◽  
Vol 63 (1) ◽  
pp. 46
Author(s):  
Mircea Dulau ◽  
Stelian-Emilian Oltean

An important stage in robust control design is to define the desired performances of the closed loop control system using the models of the frequency sensitivity functions S. If the frequency sensitivity functions remain within the limits imposed by these models, the control performances are met. In terms of the sensitivity functions, the specifications include: shape of S over selected frequency ranges, peak magnitude of S, bandwidth frequency, and tracking error at selected frequencies. In this context, this paper presents a study of the effects of the specifications of the weighting functions on the performances of robust control systems.


2020 ◽  
Vol 14 (1) ◽  
pp. 108-125 ◽  
Author(s):  
Salman Haider ◽  
Javed Ahmad Bhat

Purpose Because of growing energy consumption and increasing absolute CO2 emissions, the recent calibrations about the environmental sustainability across the globe have mandated to achieve the minimal energy consumption through employing energy-efficient technology. This study aims to estimate linkage between simple measure of energy efficiency indicator that is reciprocal of energy intensity and total factor productivity (TFP) in case of Indian paper industry for 21 major states. In addition, the study incorporates the other control variables like labour productivity, capital utilization and structure of paper industry to scrutinize their likely impact on energy efficiency performance of the industry. Design/methodology/approach To derive the plausible estimates of TFP, the study applies the much celebrated Levinsohn and Petrin (2003) methodology. Using the regional level data for the period 2001-2013, the study employs instrumental variable-generalized method of moments (GMM-IV) technique to examine the nature of relationship among the variables involved in the analysis. Findings An elementary examination of energy intensity shows that not all states are equally energy intensive. States like Goa, Rajasthan, Jharkhand and Tamil Nadu are less energy intensive, whereas Uttar Pradesh, Kerala, Chhattisgarh, Assam and Punjab are most energy-intensive states on the basis of their state averages over the whole study period. The results estimated through GMM-IV show that increasing level of TFP is associated with lower level of energy per unit of output. Along this better skills and capacity utilization are also found to have positive impact on energy efficiency performance of industry. However, the potential heterogeneity within the structure of industry itself is found responsible for its higher energy intensity. Practical implications States should ensure and undertake substantial investment projects in the research and development of energy-efficient technology and that targeted allocations could be reinforced for more fruitful results. Factors aiming at improving the labour productivity should be given extra emphasis together with capital deepening and widening, needed for energy conservation and environmental sustainability. Given the dependence of structure of paper industry on the multitude of factors like regional inequality, economic growth, industrial structure and the resource endowment together with the issues of fragmented sizes, poor infrastructure and availability and affordability of raw materials etc., states should actively promote the coordination and cooperation among themselves to reap the benefits of technological advancements through technological spill overs. In addition, owing to their respective state autonomies, state governments should set their own energy saving targets by taking into account the respective potentials and opportunities for the different industries. Despite the requirement of energy-efficient innovations, however, the cons of technological advancements and the legal frameworks on the employment structure and distributional status should be taken care of before their adoption and execution. Originality/value To the best of our knowledge, this is the first study that empirically examines the linkage between energy efficiency and TFP in case of Indian paper industry. The application of improved methods like Levinsohn and Petrin (2003) to derive the TFP measure and the use of GMM-IV to account for potential econometric problems like that of endogeneity will again add to the novelty of study.


2011 ◽  
Vol 219-220 ◽  
pp. 3-7
Author(s):  
Ning Zhang ◽  
Rong Hua Liu

An expert control system based on transient response patterns and expert system techniques is proposed in this paper. Depending on the features of the closed-loop control system determines the control decision and adjusts the parameters of the controller. The proposed method requires minimal proper information about the controlled plant and, with the linear re-excitation learning method, the system is kept satisfying the performance criterion.


2014 ◽  
Vol 18 (5) ◽  
pp. 905-918 ◽  
Author(s):  
Daniel Jiménez-Jiménez ◽  
Micaela Martínez-Costa ◽  
Raquel Sanz-Valle

Purpose – This paper aims to assess the importance of different knowledge management practices to promote organizational innovation in multinational companies. The links among internationalization, reverse knowledge transfer and social capital and organizational innovation are analyzed. Design/methodology/approach – Structural equation modeling was used to check the research hypotheses with a sample of 104 multinational companies. Findings – The results show that internalization has no direct effect on organizational innovation but a indirect effect trhrough the transfer of knowledge from external subsidiaries to the headquarter. Furthermore, this knowledge and other that comes from internal and external social capital is essential for the development of innovations. Research limitations/implications – Self-reporting by the CEOs may be the most significant limitation, as a single key informant provided the data; multiple informants would enhance the validity of the research findings. A second limitation is the cross-sectional design of the research that does not allow observation of the short- and long-term impact of the relationships among the variables. Practical implications – Organizational innovation is not an easy task. However, those multinational companies which foster knowledge management practices that generate new knowledge from external subsidiaries, internal or external social relationships, will facilitate the generation of innovations. In consequence, these companies should foster the generation of knowledge from different sources. Originality/value – The focus of the study in this paper is on multinational companies and the possibility to acquire knowledge from different sources (inside organization, external local environment and international context). Specially, focus on the transfer of knowledge from subsidiaries to headquarters (reverse knowledge transfer), as it is insufficiently investigated by current literature.


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