One of important sources of biomass-based fuel is Jatropha curcas L. Great attention is paid to the biofuel produced from the oil refinery extracted from the Jatropha curcas L. seeds. A mechanised extraction is the most efficient and feasible method for oil extraction for small-scale farmers but there is a need to extract oil in more efficient manner which would increase the labour productivity, decrease production costs, and increase benefits of small-scale farmers. On the other hand innovators should be aware that further machines development is possible only when applying the systematic approach and design methodology in all stages of engineering design. Systematic approach in this case means that designers and development engineers rigorously apply scientific knowledge, integrate different constraints and user priorities, carefully plan product and activities, and systematically solve technical problems. This paper therefore deals with the complex approach to design specification determining that can bring new innovative concepts to design of mechanical machines for oil extraction. The presented case study as the main part of the paper is focused on new concept of screw of machine mechanically extracting oil from Jatropha curcas L. seeds.
The use of bioenergy as energy derived from biofuels in the world permanently increases [1, 2]. Biomass-based fuels as renewable organic source of bioenergy have advantages (e.g., no harmful carbon dioxide emissions, reduction of dependency on fossil fuels, and versatility) and some disadvantages (e.g., requiring more land, relative ineffectiveness when compared to gasoline, and problematic supply chain) as well [3–6]. One of important sources of biomass-based fuel is Jatropha curcas L. [7–10]. Jatropha curcas L. is crop with inconsiderable potential due to its high oil content, rapid growth, easy propagation, drought tolerant nature, ability to grow and reclaim various types of land, need for less irrigation and less agricultural inputs, pest resistance, short gestation periods, and suitable traits for easy harvesting enumerated [11]. Biooil extracted from Jatropha curcas L. seeds has positive chemical properties (e.g., better oxidative stability compared to soybean oil, lower viscosity than castor oil, and lower pour point than palm oil) [12]. Jatropha significant advantage is that it is one of the cheapest sources for biodiesel production (compared to palm oil, soybean, or rapeseed) [13]. On the other hand former and recent findings [14–17] also show that researchers, economists, biochemists, farmers, machine designers, and biofuel producers should not just automatically follow the initial Jatropha hype but critically reflect on, for example, current economic situation, state biofuel policy, institutional factors, labour costs, water irrigation, local differences, and last but not least farmer’s needs. The evaluations [15], for example, opened many questions connecting with Jatropha processing profitability. One of the recommendations in [15] mentioned mechanised extraction as the most efficient and feasible method for oil extraction for small-scale farmers. Consequently one of the strategies of how to produce biofuel from Jatropha curcas L. in more efficient manner is to increase the effectiveness of oil processing machine, which would increase the benefits of small-scale farmers. This objective can be achieved through the further innovations of mechanical expellers or presses for small-scale farmers. Due to the great attention paid to this issue [18–26] innovators should be aware that further Jatropha-presses development is possible only when applying the systematic approach and design methodology in all stages of engineering design as an essential part of Jatropha-press life-cycle. Systematic approach in this case means that designers and development engineers rigorously apply scientific knowledge, integrate different constraints and user priorities, carefully plan product and activities, and systematically solve technical problems. Basic phases of the engineering design process have been in the past developed into more detailed procedures focused on the systematic development [27–33], on creative solution of technical problems [34–37], or on the preliminary and detailed embodiment design [38–40]. The correct definition of the right problem in the form of design specifications is widely regarded as a decisive step towards the effective implementation of all engineering design procedures [41–43]. Two information transformations are required to determine design specification. During the first information transformation the user’s needs are translated to functional requirements. The second information transformation takes place when converting the functional requirements to machine characteristics (design specifications) that have been selected to ensure fulfilment of specified functional requirements. By performing these transformations design assignment is then defined as an information input to concept generation phase and subsequent detailed designing. During this process various methods such as marketing research [44, 45], voice of customer (VOC) [46, 47], usability testing (thinking aloud protocol) [48, 49], Kansei engineering [50, 51], or quality function deployment (QFD) [52–54] are systematically utilized. Innovation science using function-object analysis [55, 56] or main parameter value [57] is also important to mention. For the conceptual design phase of innovation process is suitable to use modern creative techniques supporting idea generation and overcoming technical and physical contradictions based on TRIZ [58–61]. The process of concept generation is finished by choosing between concept alternatives by simple evaluation charts [28] or advanced techniques or analytic hierarchy process [4]. Since the above methods are becoming standards when upgrading technical products in 21st century it is clear that further development and innovation of machine for mechanical extraction of oil from Jatropha curcas L. require similar advanced techniques and methods.