A voltage-controllable VO2 based metamaterial perfect absorber for CO2 gas sensing application

Vanadium dioxide (VO2) based metamaterial perfect absorbers (MPAs) have high potential application values in sensing gas molecules. However, such tuning mechanism via temperature manipulation lacks the compatibility to the electronic...

Study on Air-to-Water Heat Pumps Seasonal Performances for Heating in Greece

Air-to-water heat pumps (AWHPs) is a very good option for efficient heating in the residential and commercial building sectors. Their performance and therefore the use of primary energy and CO2 gas emissions are affected by various factors. The aim of this paper is to present a study on the seasonal coefficient of performance in heating (SCOP) of AWHPs, which are available in the Greek market. The sample consists of 100 models in total, offered by 12 manufacturers, in a range of heat pump’s thermal capacity up to 50 kW. The calculation of SCOP values was performed according to the methodology proposed by the EN14825 standard. The results indicate how the heating capacity, the local climate, the supply water temperature, the compressor’s technology, and the control system affect the seasonal performance of the various AWHP models examined. Setting the SCOP ≥ 3 value as a criterion, the analysis that was carried out in four climatic zones A, B, C, and D of Greece, shows that there are many models that meet this criterion, and, in fact, their number increases from the coldest to warmer climates, in combination with lower water supply temperatures to the heating system and a control system with weather compensation.

Prototipe Pengendalian Kualitas Udara Indoor Menggunakan Mikrokontroler dengan Sensor MQ135, DHT-22 dan Filter HEPA

Indoor air pollution is a very serious health issue in comparison with outdoor air conditions. The current pandemic of COVID-19 causes people to remain indoors at all times. It is unimaginable that during this pandemic a smog-related disaster could occurs that could aggravate human respiratory diseases, thus requires additional air quality monitoring which can filter clean air into the room. The purpose of this study is to produce a prototype of air quality control that can provide a good air circulation system and hold the temperature and humidity in the room. This research was conducted with an Arduino Uno microcontroller and an MQ-135 gas sensor to detect CO2 gas and a DHT-22 sensor for measuring room temperature and humidity by comparing the results of using a HEPA filter. The research results of the prototype make it possible to generate the room temperature using a HEPA filter and air humidifier whose average is 27.7°C. Another parameter that is performed is the CO2 measurement, it is found that the average CO2 in the test using a HEPA filter and an air humidifier is 496 PPM.

Research technology of cultivation of spirulina algae with the use of CO2 hidden from the smoke of rice husk boiler

This paper presents an investigation of Spirulina algae cultivation by the CO2 gas emitted from the combustion of rice husk. The gas emitted from the rice husk combustion containing CO2 but no toxic gas of SOx. The CO2 molecules are absorbed into the micro-algae cultivation medium and then converted into the HCO3 by the assimilation of Spirulina. At the same time, the pH values are controlled to be from 8.5 to 9.5, which is suitable for Spirulina algae. At the first seven days of cultivation in Zarrouk medium the values of Spirulina algae biomass and pH increase from 0.05 g/l and 8.5 to 1.0 g/l and 10.2, respectively. On the 8th day, when the amount of 7,6 % CO2 v/v under 35–40 ºC and 1 atm is introduced into the above medium, the decrease of pH from 10.2 to 8.6 is observed. This pH value, which is maintained over the following days, is optimal for the growth yield of the Spirulina. As a result, the biomass concentration increases from 1.0 to 1.4 g/l. The obtained results are compared with those of the control sample from Zarrouk medium without gas introduction. For the latter case, the biomass reaches the maximum and then decreases. On the basis of the obtained results, the cultivation of Spirulina algae by using the CO2 molecules emitted from the combustion of rice husk can be applied practically.