A comparison of axiomatic design theory and systematic design procedure in the design of a solid state fermenter

Abstract

Design theories and methodologies are guidelines to develop design solutions. Among many, the Axiomatic design theory (ADT) and Systematic design procedures (SDP) are two well-known approaches to design. For practical applications, the choice of the design methodology is difficult as there is no study to compare them. To close in such gap in literature, this thesis presents a study on comparison of these two design approaches. To facilitate the comparison, design of a solid state fermenter was taken as a vehicle.

The fermenter chosen for this study is was used for detoxification of phorbol esters from Jatropha curcas. Jatopha curcas is a woody plant and is one of the major sources for the production of bio-diesel as it is readily available and has unique composition. Processing Jatopha curcas for biodiesel also yields protein rich Jatopha curcas seed cake. This can be used as animal feedstock, cattle fodder or live feed stock. It is however known that phorbol esters present in the seed cake hinder the utilization of the seed cake as live feed stock. Solid state fermentation by fungi is an effective process to denature phorbol esters, which has been demonstrated at the laboratory scale. Development of an industrial scale solid state fermenter (SSF) is necessary.

This study applies SDP and ADT the same deign problem of SSF and compared based on the result of the design. It is noted that in ADT, the evaluation of design alternatives neither considers the cost of the system under design nor the delivery time of the system, but SDP does. To make the comparison on the same ground, an extension of ADT enabling it to consider the cost and delivery time (or time) was developed.

Several conclusions can be drawn from this study and they are: (1) ADT and SDP are complementary to each other and the one that integrates both is more effective to design; (2) The essence of Axiom 2 of ADT is to evaluate design alternatives with all factors that lead to difficulty to realize the design, but unfortunately the information content in the current ADT literature only considers the functional or quality aspect; (3) Previous reports suggest the presence of zigzag process only in ADT, However in this study it is evident that SDP exercises the zigzag process as well; (4) the proposed formulation of information content by taking into consideration of the quality, cost, time aspects is more effective in design practice as quite often the cost and time are very important aspects to the customer.

The contribution of this thesis study is of two-fold. First, the SSF designed in this study is a pilot one in the field of the biochemical process and it has potential to be implemented. Second, this study concludes several unique findings of ADT and SDP with their relationship, which have further resulted in an integrated ADT and SDP design approach and a more complete formulation of information content capable of evaluating design alternatives from all aspects rather than the functional aspect only.