•Heat and mass transfer comparisons of desiccant coated microchannel and fin-and-tube heat exchangers were analyzed.•The heat transfer coefficient of DMHE is almost twice that of DFHE.•The mass ...transfer coefficient of DMHE is larger than that of DFHE by 15%.•Microchannel type shows excellent heat and mass transfer capacities at the cost of high pressure drop.
Two types of DCHEs, desiccant coated microchannel heat exchanger (DMHE) and desiccant coated fin-and-tube heat exchanger (DFHE), are manufactured and tested. The heat transfer, mass transfer and pressure drop performances of two DCHEs are analyzed and compared by experimental results. In the same conditions, the heat transfer coefficients of DMHE are almost twice as large as those of DFHE, no matter for sensible heat or latent heat. In dehumidification, the ratios of latent heat to total heat for DFHE and DMHE are 90% and 83%, separately. In regeneration, the ratios of latent heat to total heat for two DCHEs are both approximately 60%. The mass transfer coefficient of DMHE is 15% larger than that of DFHE. The pressure drops per unit transfer area of DMHE is almost 125% larger than that of DFHE. In a conclusion, DMHE shows lower heat capacity, higher heat and mass transfer capacity compared with DFHE.
Using data collected with the BESIII detector in e(+)e(-) collisions at center-of-mass energies between 4.178 and 4.226 GeV and corresponding to 6.32 fb(-1) of integrated luminosity, we report the ...amplitude analysis and branching-fraction measurement of the D-s(+) -> pi(+)pi(0)eta' decay. We find that the dominant intermediate process is D-s(+) -> rho(+)eta' and the significances of other resonant and nonresonant processes are all less than 3 sigma. The upper limits on the branching fractions of S-wave and P-wave nonresonant components are set to 0.10% and 0.74% at the 90% confidence level, respectively. In addition, the branching fraction of the D-s(+) -> pi(+)pi(0)eta' decay is measured to be (6.15 +/- 0.25(stat.) +/- 0.18(syst.))%, which receives significant contribution only from D-s(+) -> rho(+)eta' according to the amplitude analysis.
In this paper, two desiccant-coated heat exchangers, which are actually fin-tube heat exchanging devices coated with silica gel and polymer materials respectively, are investigated experimentally. ...Due to the hygroscopic properties of the desiccant materials, both the sensible heat and the latent heat of the process air can be handled by using this kind of heat exchanger. An experimental setup was designed and built to test the performance of this unit. It is found that this desiccant-coated fin-tube heat exchanger well overcomes the side effect of adsorption heat which occurs in desiccant dehumidification process, and achieves good dehumidification performance under given conditions. The silica gel coated heat exchanger behaves better than the polymer one. The influences of regeneration temperature, inlet air temperature and humidity on the system performance in terms of average moisture removal rate
D
avg and thermal coefficient of performance COP
th were also analyzed.
In this study, the heat and mass transfer characteristics of desiccant coated heat exchanger (DCHE) and conventional heat exchanger are compared by experiments. A general-purpose test platform is ...built to test and compare the characteristics above. Based on the designed experimental setup, two heat exchangers of different depths of fins conventional/desiccant coated are experimentally investigated and compared with the given performance evaluation standards. In addition, parametric influences of inlet air velocity, hot water temperature and cycle time are analysed. Experimental results show that compared with the conventional heat exchanger, the heat transfer capacity of DCHE is reduced by 30% because of the heat resistance produced by desiccant coating. Pressure drop and Euler number are both increased by 60% approximately for the same reason. Doubling the depth of fins increases the average moisture removal by 40% and COPth by 10%, without changing the other structure parameters.
•An experimental setup is built to test the characteristics of desiccant coated heat exchanger.•Performance evaluation standards of heat and mass transfer, coefficient of performance and pressure drop are determined.•Heat transfer capacity of DCHE is reduced by 30% compared with conventional one.•With double DCHE depth of fins, mass transfer capacity increases by 40%, while coefficient of performance increases by 10%.•Pressure drop and Euler number of DCHE both increase by 60% approximately compared with conventional one.
Using 4.7 fb^{-1} of e^{+}e^{-} collision data at center-of-mass energies from 4.661 to 4.951 GeV collected by the BESIII detector at the BEPCII collider, we observe the X(3872) production process ...e^{+}e^{-}→ωX(3872) for the first time. The significance is 7.8σ, including both the statistical and systematic uncertainties. The e^{+}e^{-}→ωX(3872) Born cross section and the corresponding upper limit at 90% confidence level at each energy point are reported. The line shape of the cross section indicates that the ωX(3872) signals may be from the decays of some nontrivial structures.
Solar powered solid desiccant cooling system is a good alternative to conventional vapor compression system. In this paper, a novel solar driven desiccant coated heat exchanger cooling (SDCC) system ...is proposed. In order to validate the feasibility of such system and to predict system performance, an integrated system model is established by combing the mathematical models of different components. The model is adopted to evaluate system performance under Shanghai summer condition with high temperature as well as high humidity ratio. It is found that SDCC system can provide satisfied supply air to conditioned indoor space from 8:00 to 17:00 in June and July, the biggest cooling powers are 2.9kW and 3.5kW, and corresponding solar COP are 0.22 and 0.24 respectively. In August, the system needs relatively short switch time (less than 2min) to provide satisfied supply air, and the corresponding cooling power can reach to 5kW. To make a good compromise between system performance and system constitution, 2min is recommended as the switch time under simulated condition in August. Also, effects of main design parameters on system performance are calculated and discussed.
We present the first measurements of the electric and magnetic form factors of the neutron in the timelike (positive q^{2}) region as function of four-momentum transfer. We explored the differential ...cross sections of the reaction e^{+}e^{-}→nover ¯n with data collected with the BESIII detector at the BEPCII accelerator, corresponding to an integrated luminosity of 354.6 pb^{-1} in total at twelve center-of-mass energies between sqrts=2.0-2.95 GeV. A relative uncertainty of 18% and 12% for the electric and magnetic form factors, respectively, is achieved at sqrts=2.3935 GeV. Our results are comparable in accuracy to those from electron scattering in the comparable spacelike region of four-momentum transfer. The electromagnetic form factor ratio R_{em}≡|G_{E}|/|G_{M}| is within the uncertainties close to unity. We compare our result on |G_{E}| and |G_{M}| to recent model predictions, and the measurements in the spacelike region to test the analyticity of electromagnetic form factors.
•Three types of novel DCHEs with variable structure sizes are tested and compared.•Ranks of influence factors in experiments are obtained by using Taguchi method.•Higher surface compactness of DCHE ...means higher heat and mass transfer capacity.•Heat and mass transfer coefficients are functions of pressure drop.
Desiccant-coated heat exchanger (DCHE) is a novel component for handling both sensible and latent heat assisted by desiccant materials. In this paper, three types of DCHEs with the same transfer surface area, DCHE A (fin pitch 2 mm, fin depth 44 mm), DCHE B (fin pitch 3 mm, fin depth 66 mm) and DCHE C (fin pitch 4 mm, fin depth 88 mm), are fabricated to make out the relationships between structure sizes and performance characteristics. The transient heat and moisture transfer performance, as well as the pressure drop passing through DCHEs, are tested and compared in depth. By using Taguchi method, the ranks of influence factors in heat and mass transfer performances are obtained. With the same transfer surface area but different surface compactness, three DCHEs show different heat and mass transfer capacities and different pressure drops. DCHE A with the highest surface compactness shows the highest heat and mass transfer capacity, while the highest pressure drop is shown as deficiency. DCHE C with the smallest surface compactness shows the highest heat recovery efficiency and the lowest pressure drop. Heat transfer coefficient of DCHE A is 14.9% greater than DCHE B, 19.6% greater than DCHE C in dehumidification process. The moisture adsorbed value of DCHE A is 9.6% greater than DCHE B, 18.2% greater than DCHE C. Pressure drop of DCHE A is 50% larger than DCHE B, and 90% larger than DCHE C. The correlations of Nusselt number and Euler number of three DCHEs are summarized by fitting the experimental data.
Using (10 087±44)×10^{6} J/ψ events collected with the BESIII detector, the radiative hyperon decay Σ^{+}→pγ is studied at an electron-positron collider experiment for the first time. The absolute ...branching fraction is measured to be (0.996±0.021_{stat}±0.018_{syst})×10^{-3}, which is lower than its world average value by 4.2 standard deviations. Its decay asymmetry parameter is determined to be -0.652±0.056_{stat}±0.020_{syst}. The branching fraction and decay asymmetry parameter are the most precise to date, and the accuracies are improved by 78% and 34%, respectively.
