•Hydrate slurry mass fraction generated in the tests ranged from 8 to 32wt%.•Circulation status for CO2 hydrate slurry in a pipeline is highly enhanced with AA.•CO2 hydrate slurry was produced and ...maintained during circulation for an hour.
Based on a proposed hydrate-based gas separation and the utilization of this technology, CO2 hydrate slurry transportation in pipeline from capture plants to storage sites is proposed in this paper. Two different transport processes are considered in the present study. The concept of CO2 hydrate slurry transportation in pipelines has many advantages over the current approaches of CO2 transportation. Transferring CO2 in hydrate slurry status reduces energy input for transportation and eliminates of hydrate blockage in pipelines thus reducing the overall cost of gas transportation. The effect of CO2 hydrate slurry formation in the absence and presence of anti-agglomerants is investigated in an experimental flow loop. The effect of four low dosages of 0.3, 0.5, 0.7 and 1.0wt% of anti-agglomerant; Tween 80 (non-ionic surfactant) on CO2 hydrate is investigated. Discussions on CO2 hydrate formation kinetics, induction time, slurry density and slurry flow within the experimental loop are provided. In the experiment, hydrate mass fraction ranged from 8 to 32%. The result indicates that CO2 hydrate slurry flow and circulation in the flow loop is significantly enhanced with anti-agglomerant.
The viscosity and thermal conductivity of ZnO nanofluids with nanoparticle shapes of nearly rectangular and of sphere, were experimentally investigated under various volume concentrations of the ...nanoparticles, ranging from 0.05 to 5.0 vol.%. The viscosity of the nanofluids increased with increases in the volume concentration by up to 69%. In addition, the enhancement of the viscosity of the nearly rectangular shape nanoparticles was found to be greater by 7.7%, than that of the spherical nanoparticles. The thermal conductivity of the ZnO nanofluids increased by up to 12% and 18% at 5.0 vol.% for the spherical and the nearly rectangular shape nanoparticles, respectively, compared to that of the base fluid (water). The shape of the particles is found to have a significant effect on the viscosity and thermal conductivity enhancements.
•Viscosity and conductivity of ZnO nanofluids increased with increase of ZnO concentration.•Viscosity and conductivity of rectangular shape ZnO nanofluid were higher than sphere's.•The Chen et al. model and the Prasher model showed minimum prediction error.
Recently, research focus has shifted from the prevention of hydrate formation in oil/gas pipelines, to the utilization of gas hydrate in various areas of application, such as cold storage, district ...cooling, and gas transportation. This study, investigated the pressure drop and flow pattern analysis of CO
2
hydrate slurry in the presence of anti-agglomerant in a flow loop. A series of experiments were carried out on CO
2
hydrate slurry with (10 to 32) % mass fractions at flow rates of (5 to 7) kg/min in the presence of (0, 0.3, 0.5, 0.7 and 1.0) wt.% concentration of Tween 80 (Polyoxyethylene (20) sorbitan monooleate) in a flow loop. The results show that the CO
2
hydrate slurry can be divided into two zones based on the pressure drop and temperature behavior; an active formation region, and a less active formation region. It was found that as the hydrate slurry mean flow rate was increased, the gradient of the pressure drop increased. From the flow visualization, three different flow regimes exist for CO
2
hydrate slurries, namely homogeneous, heterogeneous, and bedding flow, and those flow regimes were highly dependent on the hydrate fraction in the slurry mixture.
We analyzed the operating performances, such as the COP and the primary energy consumption, and LCCP, of a WSHP system by considering the local weather conditions, the water temperature, and the ...heating and cooling loads for various building types of interest (apartment, office building, hospital, data center, and department store). The WSHP system can utilize river, dam water, raw water, etc. as its hydrothermal energy sources. When the WSHP system having 500 RT is operated in an office building that is in Seoul, Korea, the monthly average COP of heating and cooling is predicted to be 3.63, while the monthly average primary energy consumption is estimated to 1678037 MJ. The WSHP system can reduce primary energy consumption by 12.80 % per year compared to the conventional system. The CO
2
emissions of the conventional heating and cooling system and the WSHP were compared by using the LCCP evaluation criteria provided by IIR. In the case of apartment, the CO
2
emission decreases from 31360608 kgCO
2
to 28375017 kg CO
2
by replacing the conventional system with the WSHP system.
This study involves the collection of data from 10 different articles to develop experimental-based models for predicting the condensation heat transfer and the frictional pressure drop. The dataset ...comprises a total of 1168 condensation heat transfer coefficients and 792 frictional pressure drop data. The applied operating range considered is within the reduced pressure of 0.1–0.95, mass flux ranging from 75 to 700 kg/m
2
s, and an inner diameter between 3.4 and 12.5 mm. We developed the models for the condensation heat transfer coefficient based on Akers et al.’s model, whose parameters are the Prandtl number, density ratio, vapor quality, and mass flux. The total error for the condensation heat transfer coefficient is ± 22.6%. The data is further categorized into two groups of the reduced pressure:
P
r
< 0.5 with an error of ± 22.9% and
P
r
> 0.5 with an error of ± 18.9%. The frictional pressure drop models were developed based on the three different ranges of the reduced pressure. The utilized non-dimensionless parameters were the two-phase multiplier (Φ
lo
2
), the Bond number (Bo), the Weber number (We), and the Martinelli parameter (X
tt
), along with the regression coefficients. Regarding the frictional pressure drop correlation, the total error is ± 32.7%, and the data is divided into three segments:
P
r
< 0.2 with an error of ± 24.6%, 0.2 <
P
r
< 0.3 with an error of ± 35.6%, and an error of ± 27.8% for the reduced pressure larger than 0.3. These correlations were developed using the MATLAB regression analysis to enhance their practicality and utility.
Efficient integration of the carbon capture and storage (CCS) process in power generation plants can help reduce global CO
2
emissions. Hydrate technology has emerged as one of the most promising ...technologies for the separation and sequestration of CO
2
. This paper compares the process energy consumption of different CO
2
capture techniques, gas transportation, and sequestration methods integrated into a pre-combustion power plant. Process modeling of a conceptualized hydrate technology-based CCS process is simulated using a coupled TRNSYS simulation software and engineering equation solver. The performance in efficiency, energy consumption, and potential energy penalty is evaluated and analyzed for three study cases. Furthermore, the energy requirement for transporting and sequestrating CO
2
in hydrate as hydrate slurry is evaluated and compared to supercritical transportation and sequestration. The results obtained show that the energy consumption of hydrate-based gas separation amounts to 70 % of the total energy consumption for hydrate-based CO
2
capture, transportation, and sequestration.
The flow characteristics of CO
2
hydrate in the presence of Tween 80 in a scaled-up test facility were investigated in order to further elucidate the potential of CO
2
hydrate slurry transportation ...in carbon capture and storage technology. Two formation processes were used to generate sufficient hydrate slurry for flow in a circulation loop of a 108 mm inner diameter pipe. The effects of Tween 80 concentrations on the four hydrate slurry parameters of pressure, temperature, density, and flow rate were studied and discussed. The results of the CO
2
hydrate slurry transportation experiments indicated that 0.7 wt.% of Tween 80 showed the optimal results for slurry stability, slurry temperature, and slurry density, but had no significant effect on slurry temperature during flowing in the loop. In all experiments, hydrate circulation was performed for an average duration of 80 min under stable conditions. The results suggest the possibility of transporting hydrate slurry over long distances under stable conditions with the addition of chemical additives.
In residential air-source heat pump systems, the refrigerant injection technique has rapidly developed in recent years due to its outstanding performance at low ambient temperatures. A numerical ...simulation model of a flash tank vapor-injection heat pump with a twin rotary compressor is newly presented in this paper. The performance of the twin rotary compressor with refrigerant injection was simulated using a loss and efficiency model. The model was validated by comparing the predictions with measured data. In addition, the model was used to analyze the performance characteristics of the vapor-injection heat pump according to the cylinder volume ratio of the twin rotary compressor. Based on the simulation results, optimum cylinder volume ratios were suggested for various design conditions, including for the fixed first cylinder volume, the fixed total cylinder volume, and the fixed heating capacity.
► A numerical model of the vapor-injection heat pump was developed. ► The effect of the cylinder volume ratio on the performance was analyzed. ► The optimum cylinder volume ratios varied with the fixed design condition.
The condensation heat transfer coefficient and pressure drop of CO2 in a multiport microchannel with a hydraulic diameter of 1.5 mm was investigated with variation of the mass flux from 400 to ...1000 kgm−2s−1 and of the condensation temperature from −5 to 5 °C. The heat transfer coefficient and pressure drop increased with the decrease of condensation temperature and the increase of mass flux. However, the rate of increase of the heat transfer coefficient was retarded by these changes. The gradient of the pressure drop with respect to vapor quality is significant with the increase of mass flux. The existing models for heat transfer coefficient overpredicted the experimental data, and the deviation increased at high vapor quality and at high heat transfer coefficient. The smallest mean deviation of ±51.8% was found by the Thome et al. model. For the pressure drop, the Mishima and Hibiki model showed mean deviation of 29.1%.
•Flow complexity is dominant factor in condensation with microchannels.•Existing models highly overpredicted condensation heat transfer coefficient of CO2.•The Mishima and Hibiki model was suitable for predicting pressure drop.
The condensation heat transfer characteristics of CO2 flowing in a horizontal smooth tube were investigated. The tube diameter was 5.15 mm. The condensation temperature ranged from −10 to 5 °C, and ...the mass flux was from 600 to 1000 kg m−2 s−1. When the temperature changed from 0 to −10 °C, the increase rate of the heat transfer coefficient was from 9.4 to 14.6%, and the pressure drop increased from 6.2 to 52.9%. When the mass flux increased from 600 to 1000 kg m−2 s−1, the heat transfer coefficient increased from 6 to 35%, and the pressure drop increased from 60 to 165%, which were dependent on the condensation temperature. The increases come from the change of vapor velocity and thermophysical properties with condensation temperature. Considering large variation of mass flux from 200 to 1200 kg m−2 s−1 by including the existing studies, the effect of mass flux on condensation heat transfer coefficient was minor.
► Heat transfer coefficient increased with decrease of the condensation temperature. ► Pressure drop decreased with increase of the condensation temperature. ► Existing models overpredicted effect of mass flux on heat transfer coefficient. ► Liquid film thickness and the interface shape are major parameters for new model. ► The Cavallini et al. model was suitable for predicting pressure drop.
