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•Non-ideal mathematic model for hollow facilitated transport membrane module is established.•Pressure drop, concentration polarization and Joule-Thomson effect have significant ...influence on separation process.•Hollow facilitated transport membrane module with short fiber length, moderate packing fraction and high fiber inner diameter is promising for practical application.
Membrane separation technology has been regarded as a promising alternative for carbon capture process due to its low consumption and low footprint. Facilitated transported membranes exhibit attractive CO2/N2 separation performance due to the existence of CO2-philic reactive carriers. However, the highly pressure and temperature dependent CO2 permeance of it, as well as non-ideal effect, make the simulation of carbon capture process based on simplifying model challenging. Herein, we established a rigorous model for hollow fiber facilitated transport membrane considering both non-ideal effect and variable permeance. This rigorous model was applied for post-combustion carbon capture, and compared with simple model which only considering variable permeance. It was found that rigorous model has a 44%-55% lower carbon capture capacity due to the declined driving force and permeance. Pressure loss accounts for the deviation at low stage cut (10%), while Joule-Thomson effect and concentration polarization effect become greater at high stage cut (20%). Thanks to the mild condition of post combustion flue gas, the impact of real gas behavior can be neglected. Moreover, the attractive configuration of hollow fiber facilitated transport membrane was found to be with relative short fiber length, moderate packing fraction and large fiber inner diameter.
Theoretical Model for Photovoltaic Panel Thermal Analysis Lupu, Ana-Georgiana; Hristoforou, Evangelos; Tcaciuc, Gabriel-Dumitru ...
Bulletin of the Polytechnic Institute of Iași. Machine constructions Section,
03/2022, Volume:
68, Issue:
1
Journal Article
Peer reviewed
Open access
The process of energy conversion of incidental solar radiation to useful electric energy in photovoltaic (PV) panels is affected by several external factors, of which panel operational temperature is ...of utmost importance. The present study attempts to clarify the theoretical components of thermal behaviour of PV panels, by taking into account the detailed structure of thermal resistances of panel layers. The numerical model, developed from the theoretical analysis, shows a good agreement with experimental data provided by manufacturer for the photovoltaic panel Suntech STP280 - 24/Vd.
Drying is conducive in extending the storage life of fresh harvested onion. Currently, direct sun drying is not suitable in terms of fluctuating weather conditions. Rotary dryer assisted by ...combustion heating is a viable option to speed up onion drying process. In this case, 10 kg of fresh onion was placed in a rotary dryer operating for 2 hrs at 40°C and 14.6 m/s of air velocity. Moisture content was observed at every 30 mins and drying rate was predicted using several mathematical models. The drying temperatures were 50, 60, 70°C and the drying procedures were repeated. Results showed that the rotary dryer method can improve drying performance compared to the chamber and tray dryer methods and the drying rate of onion bulb drying can be well represented by the Page’s model with R 2 value near to 1, and the lowest average chi-square (X2 ) of 0.00027.
One characteristic of a person having a critical thinking disposition is engaging in the activity with reflective skepticism. Skeptical attitudes can encourage a person to reflect so as to produce a ...correct conclusion and make the right decision. This article aims to determine: (1) the cause of students skeptic in dealing with illlogical mathematics problem and (2) the phase involved in skeptic and decision making on ill-logical mathematics problem. This research is a qualitative research with explorative descriptive research type. The subject of this study consisted of two students who were skeptical of ill-logical mathematics problem. The data were collected through a test, direct observation, and interview. The results of data collection were analyzed through data reduction stage, data presentation and conclusion of findings. The results of this study indicate that: (1) there are two causes of skepticism: (a) the presence of cognitive conflict and (b) the presence of two conflicting outcomes; (2) the phases involved in skepticism and decision making on the Ill-logical Mathematics problem from stimulus, skeptic, reflective, and decision making.
This research aimed to produce a study of students' mathematical concept understanding abilities in classes with Realistic Mathematics Education (RME) model learning and classes that did not receive ...RME model learning. This research was a quantitative method of quasi experiment model designed in the form of non-equivalent control group design involving two research classes determined using purposive sampling technique. The instrument used was a test of students' mathematical concept understanding ability in the form of description questions. The data analysis technique in this study used an independent sample t-test and N-gain score. The results of the analysis showed that students' mathematical concept understanding ability in the class that received RME model learning was better than that of those who did not receive RME model learning. The increase in students' mathematical concept understanding ability in the class with RME model learning was in a low category with an average gain score of 0.025. The low increase is due to the limited learning time at school during the adaptation period of new habits, so that learning with the RME model does not run effectively.
Anxiety towards a particular subject is experienced by most students in various schools, especially in mathematics. This research aims to determine the influence of self-efficacy and self-anxiety on ...mathematics in one of the schools in Cirebon City. The sample was selected using a purposive sampling technique, with a sample size of 40 students, each representing a higher grade. This study employs a quantitative approach. The data analysis techniques used are regression analysis and ANOVA test. The results of the research conclude that self-efficacy does not have a significant influence on self-anxiety in mathematics. Based on the R-Square analysis, a coefficient of determination of 0.238 is obtained, indicating that self-efficacy accounts for 28.5% of the influence on self-anxiety, while other variables influence the remaining 71.5%. Meanwhile, the ANOVA analysis shows a value of ÿ1 of 0.232. This means that each unit increase in the coefficient of self-efficacy will influence 0.232 on self-anxiety. Additionally, ÿ is equals 45.146, which means that if self-efficacy (d) is equal to 0, self-anxiety will be equal to 15.382. Therefore, it can be concluded that self-efficacy does not have a significant influence on self-anxiety in students, particularly in the subject of mathematics.
This study aims to improve learning outcomes by applying learning models to Realistic Mathematic Education on material for arithmetic operations on fractions in class V SDN 1 Karangkendal, Kapetakan ...District, Cirebon Regency. This research is a Classroom Action Research conducted in 3 cycles. The subjects of this study were 29 grade 5 students at SDN 1 Karangkendal, Kapetakan District, Cirebon Regency. Research data was collected through tests. This data analysis uses a qualitative descriptive analysis technique. The results showed increased learning outcomes in fifth-grade students at SDN 1 Karangkendal, Kapetakan District, Cirebon Regency, through a learning model, Realistic Mathematic Education. The increase in student learning outcomes is shown by the increasing number of students who meet the Minimum Mastery Criteria scores. In cycle one there were 62.1% of students achieved the Minimum Mastery Criteria scores. Then, in cycle two there were 75.9% of students had achieved the Minimum Completeness Criteria score; in cycle three, 86.2% of students had achieved the Minimum Mastery Criteria score. Based on these results, there is an increase in student learning outcomes with the application of learning models Realistic Mathematic Education on material for arithmetic operations on fractions at SDN 1 Karangkendal, Kapetakan District, Cirebon Regency.
In this article, we ask whether it is possible to reinforce problem design skills in secondary school mathematics teachers around the UN Sustainable Development Goals (SDGs), so that young students ...can try out a first numerical approach to sustainable development. If this is possible, we ask whether it would significantly improve their relationship with sustainability and their perception of the usefulness of mathematics. The present paper aims to proactively contribute to the field of civic education through the design of original math problems combining math secondary education curriculum with the predicament of the 2030 Agenda and the 17 interlinked SDGs. Conceived as a qualitative research tool for teacher training, generating adequate resources for their professional practice, five of these chosen workshop activities have been presented to a group of forty-seven students who were asked to complete a questionary afterwards about their attitude towards the proposal. The article’s main findings are that SDGs are a powerful source of inspiration for problem design grounded in real-world contexts and that students of this age are mostly ready to feel curiosity and motivation about the mathematical approach to sustainability and their capacity to analyze real data, regardless of the inevitable oversimplification of the problem.
The purpose of the research is to determine the ability of mathematical representation of students based on the level of socio mathematical norms owned by students. This research uses a descriptive ...qualitative method. The subjects were six students who had high, medium, and low sociomathematical norm categories. This study used questionnaires, written tests, and interviews as data collection instruments. Rasch model method for questionnaires and written tests as a data analysis technique and in interviews analyzed using data reduction, data collection, and conclusion drawing using MAXQDA. The results of this research are: 1). Students with high sociomathematical norm categories have high mathematical representation abilities and so do students with medium and low sociomathematical norm levels, 2) the characteristics of students' representation abilities tend to have symbolic ability indicators and 3) the characteristics of students' sociomathematical norms in this study tend to mathematical communication indicators.
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