Performance comparison of different control strategies for heat exchanger networks

In this article, the dynamic responses of heat exchanger networks to disturbance and setpoint change were studied. Various control strategies, including: proportional integral, model predictive control, passivity approach, and passivity-based model predictive control were used to monitor all outlet temperatures. The performance of controllers was analyzed through two procedures: 1) inducing a ±5% step disturbance in the supply temperature, or 2) tracking a ±5°C target temperature. The performance criteria used to evaluate these various control modes was settling time and percentage overshoot. According to the results, the passivity-based model predictive controllers produced the best performance to reject the disturbance and the model predictive control proved to be the best controller to track the setpoint. Whereas, the ensuing performance results of both the PI and passivity controllers were discovered to be only acceptable.

Particle formation of ibuprofen-supercritical CO2 system from rapid expansion of supercritical solutions (RESS): A mathematical model

10.1016/j.powtec.2005.03.020Powder Technology1542-383-94POTE

A continuum model for carbonation curing of fibre-cement composites

Accelerated carbonation curing of cellulose fiber-cement composites is known to improve their durability in the form of decreased porosity and increased mechanical properties. In addition, because carbonation results in a decrease in the alkalinity of cement paste, it makes cement less aggressive towards the cellulose fibers. The properties of the composite can be controlled by adjusting carbonation curing time, carbonation curing pressure as well as mechanical rolling pressure. In this context, a continuum model is proposed that couples the process of hydration of cement with heat, moisture and CO2 transport, including precipitation of CaCO3, change of porosity because of hydration as well as carbonation and water release and consumption. Experimental data on carbonation curing of a cellulose fiber-cement composite has recently become available, which serves to validate the model. Preliminary results indicate that the model is able to predict within reasonable accuracy the depth of carbonation

Rational use of Jatropha curcas L. in food and medicine:from toxicity problems to safe applications

<p>Jatropha curcas L. has become an important plant for biorefinery and production of biodiesel. From its ethnobotanical use, the plant is known for several activities which are associated with high toxicity. The latest development in engineering technology enables detoxification of native oil and other parts of the plant for new pharmaceutical purposes. Hence a revised look to the rich metabolic spectra of partly structurally rare secondary compound becomes an interesting field of research to be explored. In this review, we discuss recent developments in the technology of detoxification process and give insight about how this ethnomedicinal plant can be applied to new fields of experimental medicine. The review highlights recent data on biological activities and discusses concepts and strategies for turning a poison plant into a valuable crop with high pharmaceutical potential.</p>