• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.31 no.8
• /
• pp.694-701
• /
• 2007

The applications of a transcritical $CO_2$ cycle into water heaters show advantages over conventional systems in the respect of power consumption and heating efficiency because the $CO_2$ cycle has a high compressor discharge temperature. Besides, the heating performance of the transcritical $CO_2$ cycle can be improved by optimizing operating conditions. In this study, the heating performance of a variable speed $CO_2$ heat pump was measured and analyzed by varying refrigerant charge amount, EEV opening, compressor frequency and outdoor temperature. As a result, the optimum normalized charge for heating was 0.226. The COPs at the compressor frequencies of 40, 50 and 60 Hz were 2.94, 2.75 and 2.25, respectively. The heating performance of the $CO_2$ cycle with charge amount was more sensitive than the cooling performance. Moreover, the heating performance was improved significantly by optimizing of compressor frequency and EEV opening.

• Journal of the Korea Institute of Building Construction
• /
• v.6 no.1 s.19
• /
• pp.123-130
• /
• 2006

After the new house symptoms recently, room environment pollution problem of building syndrome and so on is becoming research about ways to solve this being risen. Is taking advantage of nature data by building materials by one of this way, but Friendly Environmental performance examination for structure material is insufficient misgovernment being real condition that put emphasis in ability as most embellishment and in finish. Environmental examination is insufficient misgovernment on factor itself as structure material. Also, being real condition that radon that is responsible for lung cancer occurrence next to smoke in building materials such as concrete and so on is happened, the danger is reported much through mass communications and research paper etc. Therefore, this research measured radon release amount and the carbon dioxide adsorption rate for physical special quality measuring and Friendly Environment Efficiency that follow to 'KS F 4004 Concrete bricks' regulation after manufacture Concrete Bricks utilizing charcoal that is nature material by sand. This study finding carbon dioxide density appeared and displayed effect that charcoal Controls radon release that happen in Concrete Bricks to maximum 74% that decrease to best 95% though decreased the charcoal addition rate increases.

• Journal of Biosystems Engineering
• /
• v.18 no.1
• /
• pp.60-70
• /
• 1993

In this study, the environment variations and distributions in different types of greenhouses were measured and analyzed. The elements of environment analyzed were temperature, relative humidity, illumination, carbon dioxide and wind velocity. The analyzed greenhouse types were auto-multi type which has an automatic environment control system and multiple continuous arches, regular-multi type which has an temperature control system and multiple continuous arches, and single arch type which has no environment control system without manual temperature keeping method. The results of this study can be used for the greenhouse building and managements.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.19 no.9
• /
• pp.669-678
• /
• 2007

In this study, the ventilation characteristics is investigated numerically of the longitudinal ventilation method in the curved long road tunnel. Numerical work has been conducted for the jet fan location by utilizing the commercial finite-volume code, FLUENT. Configuration of the tunnel is three-lane, 1600 m long, $120m^2$ in area, 3000 m curvature radius. The velocity profile, distribution of mono-dioxide carbon and flow rate of air are examined in the tunnel. Through the analysis, it is found that the difference of ventilation flow rate Is a little by the jet fan location, but tunnel outlet setup (CASEIII) of jet fans is the most efficient concerned with CO concentration.

• KIEAE Journal
• /
• v.10 no.1
• /
• pp.19-24
• /
• 2010

Modern people are spending most of time in interior area. Indoor air environmental problem is one of the most effective factors influenceable to human health. Furthermore, saving energy and making ventilation system for pleasant indoor environment are necessary when it is faced shortage of energy over the world. In our country's case, it is already imposed that required quantity of air ventilation in buildings is 0.7 times per hour on "The regulation on building engineering system". As on the rise of the interests about Indoor air environment, Heat and Carbon dioxide emissions from User's metabolism, activity, furniture, and construction materials etc. could be the causes of Indoor air pollution. If these materials stays in Indoor air for so long, it could directly influence the user's health condition with a disease. As of building's sterilization improved that raised more mechanical ventilation. It also leads much energy waste in a period of high price of fossil fuel. Therefore, the way that saves energy and effective control of indoor ventilation is urgently needed. So, this study places the purpose on validating volume of indoor ventilation and user's comfortable degree by comparison CO2 emission rate through changing floor temperature.

• Clean Technology
• /
• v.24 no.1
• /
• pp.50-54
• /
• 2018

In this work, N-methyl-2-pyrrolidone (NMP) was added into diethylenetriamine (DETA) aqueous solution for high $CO_2$ loading via phase splitting of absorbents during $CO_2$ absorption. Immiscible two phases were formed in the range of more than 30 wt% of NMP in 2 M DETA + NMP + water absorbents because of low solubility of DETA-carbamate in NMP solution. As the composition of NMP in the absorbents increased, the difference of $CO_2$ loading between each phase increased and the volume of bottom phase decreased. In $CO_2$ absorption in packed column by 2 M DETA + NMP + water absorbents, the absorption rate decreased in the range of more than 40 wt% of NMP. It is due to the increasing of mass transfer resistance in liquid film of absorbents at the high concentration of NMP. DETA + NMP + water absorbent is expected as the promising one for reducing the regeneration energy of absorbents according to volume reduction of $CO_2-rich$ phase.

• Clean Technology
• /
• v.10 no.4
• /
• pp.221-228
• /
• 2004

Ethoxylated Nonyl Phenol Series (NP-series), nonionic surfactants, were applied for forming microemulsions in supercritical $CO_2$. Measurement results of the solubility in supercritical $CO_2$ are in the following; NP-series were high soluble in carbon dioxide in spite of the fact that those were not $CO_2$-philic surfactants traditionally well known. Water in $CO_2$ microemulsions were also formed stably. A complexation of hydrophilic lengths for $CO_2$-philic parts of NP-Series surfactants was optimized by NP-4 surfactant(N=4) for forming the microemulsions through the experiments. Formation of microemulsions was confirmed by measuring the UV-Visible spectrum through a spectroscopic method and existence of water in the microemulsions was confirmed as well. In order to apply it for a metal surface treatment or electroplating, an experiment for forming acid(organic, inorganic) solution in $CO_2$ microemulsions was carried out. Ionic surfactant in the reaction to an acid solution became unstable to form microemulsions, however, nonionic surfactant was formed stably in the reaction. Results of the study will be utilized for expanding the application scope of supercritical $CO_2$ which is an environmental-friendly solvent.

• The Korean Journal of Mycology
• /
• v.37 no.1
• /
• pp.60-64
• /
• 2009

Effects of $CO_2$ concentration (500, 800, 1,000 and 1,500 ppm) on the initiation and development of fruit body of Grifola frondosa on sawdust cultivation were studied. Optimum concentrations of carbon dioxide for the initiation and development of the fruit body showed the ranges from 500 to 800 ppm. Fruit body initiation was accelerated at lower than 800 ppm $CO_2$ exposure but the maturing of the fruit body was not influenced by above treated $CO_2$ concentrations. The higher ratio of primordial formation, faster fruit body initiation and higher yield were obtained at below 800 ppm of $CO_2$ level, whereas over 1,000 ppm of $CO_2$ levels showed abnormal and lower quality of fruiting bodies. Based on the above results, it is concluded that the favorable $CO_2$ level for bag culture of G. frondosa was below 800 ppm.

• Applied Chemistry for Engineering
• /
• v.22 no.3
• /
• pp.301-307
• /
• 2011

Optimal culture conditions of Spirulina platensis NIES 39 have been established using different types of light sources. Several types of photobioreactors were designed and the increase of biomass, the amount of $CO_2$, fixation and the production of chlorophyll content were studied. The result revealed that the input conditions of a 10 min period per 4 h at the condition of 5% $CO_2$ and 0.1 vvm, were excellent in the growth. The growth showing the maximum biomass accumulation is limited to 1.411 g/L when using the fluorescent bulb and the low powered surface mount device (SMD) type LEDs which were equipped-inside in the photobioreactor. However, the biomass exceeded up to 1.758 g/L level when a high powered red LED (color temperature : 12000 K) photobioreactor system was used. The $CO_2$ fixation speed and rate were increased. Although the total production of chlorophyll content undergoes a proportional increase in the biomass, the net content per dry cell weight (DCW) showed the higher production with a blue LED (color temperature : 7500 K) light than that of any other wavelengths. The carbon dioxide loss was marked as 0.15% of the inlet gas (5% $CO_2/Air$, v/v) at the maximum biomass culture condition.

• Preventive Nutrition and Food Science
• /
• v.6 no.4
• /
• pp.240-243
• /
• 2001

Fresh pasta was packaged in a modified atmosphere of 22% $CO_2$/78% $N_2$ and compared with a control air package for its quality changes during storage at 8$^{\circ}C$. The modified atmosphere packaging suppressed the microbial growth of total aerobic bacteria and yeasts/molds with a concomitant reduction in the rates of physical and chemical quality changes, and thus successfully extended the shelf life of fresh packs from 20 days of air packs to 40 days based on microbial criterion of 10$^{6}$ cfu/g. The shelf life extension was greater when the initial microbial quality of the product was better.