Luiz Antonio Rasia

This article shows the importance of applying new teaching-learning methodologies and tools to structure a potentially significant teaching unit in ​​refrigeration and air conditioning. In this study, an experimental bench was set up and different temperature and pressure measurements were taken to obtain the enthalpies of the condensation and evaporation systems of an air conditioning prototype. Initially, the focus was on the conceptual description of the methodological tools and a learning project was structured which, in short, resulted in an organized, creative and motivational laboratory product for a teaching unit of six refrigeration and air conditioning classes in an undergraduate course in mechanical engineering. After assembling the prototype, the academics visualized the physical phenomena involved in the air conditioning and thermal conformation processes. Temperatures were measured in different pressure ranges and enthalpies were determined at all specified measurement points. In this way, it was verified that the maximum efficiency of refrigeration systems occurs in the range of 90 psi – 100 psi, with the increase in performance occurring during the passage of the refrigerant fluid in the condenser. The use of these teaching-learning tools applied in the mechanical engineering course was fundamental, in addition to motivating and understanding the physical phenomena involved in refrigeration processes.

We are developing Santa Rosa municipality as a smart and sustainable region that stimulates innovation. A place that will take advantage of the data–driven economy and data–centric applications with Equality, Diversity and Inclusion (EDI) as a priority. To this end, have built a pilot smart city lab for testing technologies in real-life conditions; we are currently exploring decentralised technologies and technologies with low environmental cost. Also, we are following competency frameworks for smart cities rather than deploying technologies indiscriminately. 12 years of work have produced tangible results and practical experience that we share in this paper.

Manufacturing environmentally friendly electronic components is a major challenge for traditional microelectronics companies. Some factors make the industry polluting and pose a high risk of accidents since they employ the use of chemical or radioactive products during complex manufacturing processes and discard at end of useful life. Electronic waste, in addition to being an environmental problem, becomes logistically expensive to reuse. Thus, the development of new technologies focusing on the manufacture of green or ecological components, waste reduction, simple and correct disposal are instruments of study and increasing use. In this work, we present a proposal for a humidity sensor using paper and graphite. Paper is a biodegradable material and can be used in sensors, although its processing is complex. The sensors developed use simple manufacturing techniques and are biodegradable. We verified the functioning of humidity sensors through mathematical-experimental tests showing the sensitivity of the devices using a micro controlled system.

This work presents the development and characterization of a process for manufacturing test specimens using thermoplastic polyurethane (TPU) on paper substrates, which serve as elastomeric substrates for the manufacturing of piezoresistive sensor devices using the Graphite on Paper (GoP) technique. The study of piezoresistive sensor elements is based on their behavior in response to physical stimuli such as mechanical stress or compression, resulting in variations in electrical resistance obtained from the deposition of graphite films on paper, combined with the elastomer. By leveraging the piezoresistive effect of graphite, innovative technological solutions are sought, enabling the creation of different types of sensors for measuring and monitoring a wide range of physical quantities. The proposed process utilizes commonly available materials in the market and offers a low-cost alternative compared to traditional techniques used for semiconductor-based devices. To create the test specimens, a perforated matrix made of polylactic acid (PLA) was produced using 3D printing, with dimensions specified in ISO 1924-2/2008, and a thickness limitation of 2 mm. TPU is deposited into the perforated grooves of the developed matrix on the paper substrate, filling the spaces intended for the addition of the elastomeric polymer. The deposition process is carried out similar to silk-screen printing, ensuring uniform thickness of the test specimens. The curing process takes place over a period of 48 h at room temperature under the weight of granite structures covered with PVC sheets. After curing, the test specimens are demolded. The obtained results consist of TPU + Paper strips with an average thickness of approximately 2.1357 mm, with a mean thickness variation of 0.10688 mm, representing an average variation of 4.947 % among the strips. By disregarding the highest and lowest results from the measurement series, samples with an average thickness of 2.1327 mm and variations of 0.09250 mm were obtained, representing an average thickness variation of 4.328 %. These results are promising for the development of flexible sensor devices for applications in industrial equipment, soft robotic systems, healthcare, and bioengineering fields.