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This paper presents a novel triple heat sources-driven absorption heat pump system. The exhaust gas is used as the heat source for a high-pressure generator. The superheated refrigerant vapor generated by the high-pressure generator is used for heating the solution in the low-pressure generator 1 by releasing the latent and sensible heat. The low-temperature solar thermal energy serves as the heat source of the low-pressure generator 2. The geothermal energy supplies heat to the evaporator. Heat discharged from the condenser and the absorber is supplied to the air conditioner heat medium water. The high- and low-pressure generators are coupled to each other through an ejector. The introduction of the ejector reduces the pressure of the low pressure generator 2 below the condensing pressure so that the lower temperature solar thermal energy can be utilized. An experimental setup for this heat pump cycle is built, and an experimental investigation is carried out. The influences of the independent variables on the key internal operating parameters and heating performance have been investigated. Experimental studies show that when the hot air temperature is 213 °C and the temperature of the hot water is 43.5 °C, a heating capacity of 26.6 kW can be achieved with a heating performance coefficient greater than 1.7. In this way, an efficient and full use of waste heat is realized, and the results can provide an important basis for the design and wide application of low-temperature solar thermal and geothermal energy.

In this work, a feed-forward artificial neural network (ANN) was developed for the calculation of isobaric heat capacity of pure HFC and HFO refrigerants in liquid phase. First of all, a total of 1142 available experimental data points for different pure HFC or HFO refrigerants were collected and evaluated before being used to train and test the network. By a trial-and-error method, optimum structural of the network was found out to be an input layer using four dimensionless input parameters, one hidden layer with 34 neurons, and an output layer with reduced residual heat capacity as output. The ANN was applied for 12 different refrigerants, and the predicted isobaric heat capacity showed satisfactory agreement with experimental data. The overall average absolute deviation (AAD %) and maximum absolute deviation (MAD %) were 0.383% and 5.92% respectively.

It is very important to develop a reliable method for the application of the pulsating heat pipe (PHP), however, the currently proposed heat transfer correlations or theoretical models still have some apparent shortcomings, such as great deviation and poor flexibility. Considering the advantages of artificial neural network (ANN) in analyzing complex systems, a fully connected feed forward ANN model was used to predict the thermal resistance of a closed vertical meandering PHP with water. The Number of turns, filling ratio, heat flux, inner diameter and the length ratio of evaporation section were selected as the input parameters. By applying a trial-and-error method, the neuron number in the hidden layer was optimized to be 10. A total of 221 points of experimental data under different working conditions collected from the published literature were applied to build the ANN model. The results showed a good agreement between the experimental data and the ANN model with the MSE and correlation coefficient of 0.0025 and 0.9962, respectively. Furthermore, the influence of the heat flux on the relative deviation was also investigated. It suggested that the ANN model could have better prediction results when the heat flux was within the range of 6500–14,500 W/m2.

In this work, isobaric heat capacity of liquid refrigerants mixtures was investigated experimentally and theoretically. First of all, experimental isobaric heat capacity data of a representative HFC-32+HFO-1234ze(E) binary mixture was obtained by a modified Calvet calorimeter at different temperatures and concentrations. After that, a previously proposed corresponding state equation, which was used for estimation of isobaric heat capacity of pure liquid HFCs and HFOs refrigerants, was extended to mixtures. Different mixing rules for pseudo-critical parameters were tested and a comparison between predicted values and experimental data was carried out in search of a best mixing rule. In the end, the corresponding state equation coupled with the selected mixing rule was applied to other binary mixtures R-410A, R-507A and ternary mixtures R-404A, R-407C. It was found that the calculated results agreed well with their fundamental Helmholtz equations of state. The average absolute deviation was 0.88% and maximum absolute deviations were no more than 1.90%.

This work proposed a corresponding state equation for the prediction of isobaric heat capacity of liquid hydrofluorocarbon (HFC) and hydrofluoroolefin (HFO) refrigerants. The equation was derived from classic corresponding state principle and rigorous data analysis. With known acentric factor, critical point and ideal gas isobaric heat capacity, the equation could provide predictions for isobaric heat capacity of liquid refrigerants at a wide state range with satisfactory accuracy. By means of testing available experimental data, the overall prediction accuracy of the equation was confirmed to be 1.78%, which was much better than other prediction methods.

The vapour-liquid equilibrium (VLE) data of four ternary solutions HCOOK + [Emim]Ac /[Emim]Br / [Emim]Cl / [Emim]NO3 + H2O were measured using the boiling method at the temperatures from 305.78 K to 387.08 K, at solute (HCOOK + IL) mass fractions (w) between 0.2 and 0.5. A total of 234 data points (w = 0 included) were obtained and correlated with empirical Antoine-type equations. The absolute average relative deviations (AARD %) between calculated and measured vapour pressures were 0.58%, 0.50%, 0.49%, 0.63%, respectively, which showed good agreement. The comparison of the experimental and standard data and combined uncertainties of the experimental data confirmed good reliability of the experimental method and apparatus. The four ternary solutions with ILs as additives have lower vapour pressure compared to the corresponding binary solutions without ILs. The results showed that the four ternary solutions of HCOOK + [Emim]Ac / [Emim]Br / [Emim]Cl / [Emim]NO3 + H2O can be the alternatives for traditional dehumidification and absorption media. [Emim]Cl has the best ability to reduce the vapour pressure of HCOOK + H2O at the solute (HCOOK + IL) mass fraction of 0.4 and 0.5. The [Emim]Ac has the most effect reducing the vapour pressure of HCOOK + H2O at the solute (HCOOK + IL) mass fraction of 0.3.

Isobaric heat capacities of compressed liquid 1,1,1,3,3-pentafluoropropane (R245fa) and 1,1,1,3,3,3-hexafluoropropane (R236fa) were measured by scanning calorimetry. The experimental system basically consists of a calvet calorimeter (Setaram C80) and a pressure balance unit. A total of 55 data points for liquid R245fa and 52 data points for liquid R236fa were obtained at temperatures from (315 to 365) K and pressures up to 5.5 MPa. The uncertainties for the heat capacity of R245fa and R236fa were estimated to be (1.8 and 1.6)%, respectively. The experimental data was correlated to an empirical equation, the form of which was decided by stepwise fit method. The average absolute percentage deviations between the data points and the equation were (0.23 and 0.10)% for R245fa and R236fa.

In this context, a two-stage absorption-transcritical hybrid refrigeration system is proposed. R744 is chosen as a refrigerant for the transcritical heat pump subsystem and LiBr-H 2 O working pair for the two-stage absorption refrigeration subsystem. Based on the mathematical and physical models, theoretical investigation is carried out on its performance. The main effects are discussed on COP net (the ratio of cooling capacity powered by low-grade heat to the low-grade heat consumption for the hybrid system) and COP mt (the ratio of cooling capacity powered by mechanical work to the mechanical work consumption for the hybrid system). Comparing with the normal two-stage absorption refrigeration system, theoretical results show that COP net could be improved up to about 55% when the refrigeration temperature is 7 °C. In addition, COP mt are more than 50% higher than that of the conventional transcritical refrigeration system. It is also found that both 45–55 °C low-grade heat and condensing heat could be used as actuating heat of the two-stage absorption refrigeration subsystem.

2,3,3,3-Tetrafluoropropene (R1234yf) is an environmentally friendly promising alternative to 1,1,1,2-tetrafluoroethane (R134a) in air conditioning applications. The heat capacity of R1234yf in liquid phase was investigated in this study. The measurements were carried out with a modified heat conduction calorimeter. A total of 74 data points were obtained among 305–355 K and 1.5–5 MPa. The uncertainty of the heat capacity measurements was estimated to be less than 1.7%. An empirical equation was correlated to reproduce the experimental result with its terms chosen by a stepwise method. The maximum deviation between the correlating equation and the experimental data was 1.5%. Furthermore, saturated liquid heat capacity of R1234yf was obtained by extrapolating the correlation to saturated pressures. Finally, a comparison was done between the present data and literature experimental data and calculations from a fundamental equation of state.

Three kinds of lithium chloride desiccants were selected, which are considered to be potential and interesting working fluids for a desiccant/dehumidification or absorption refrigeration system, and their isobaric specific heat capacities were determined in this context. Experiments were conducted at a high accuracy twin-cell scanning calorimeter. The temperature accuracy and heat flux resolution of the calorimeter are ±0.05 K and 0.1 μW respectively. The data of lithium chloride + water and lithium chloride + triethylene glycol (TEG)/propylene glycol (PG) + water systems were achieved at temperatures from 308.15 K to 343.15 K and atmospheric pressure. The mass fraction of LiCl ranged from 15% to 45% in the LiCl + H2O system, and the mass fraction of LiCl and glycol ranged from 10% to 23.3% and 20% to 46.7% in the ternary systems respectively. Based on the experimental heat capacity data, a universal empirical formula was correlated as a function of temperature and solute mass fraction. In the experimental mass fractions and temperatures range, the average absolute deviation (AAD) between experiment results and calculated values is no more than 0.15%, and maximum absolute deviation (MAD) is within 0.38%. These thermodynamic data of lithium chloride solutions can be effectively used for analysis and design of desiccant/dehumidification systems and absorption refrigeration systems in both refrigeration and chemical industry.

Motivated by some new experimental data, we carry out a phenomenological analysis of D→KπD→Kπ decays including both Cabibbo favored and doubly Cabibbo suppressed modes. Two asymmetries, R(D0)R(D0) and R(D+)R(D+), which are generated through interference between Cabibbo favored and doubly Cabibbo suppressed D→KπD→Kπ transitions, are predicted. The relative strong phase, δKπδKπ, between D0→K−π+D0→K−π+ and D0→K+π−D0→K+π− decays, is estimated. The theoretical results agree well with the current measurements.

By employing vector meson dominance to establish the electromagnetic interactions of hadrons, the electromagnetic self-energy of the neutral pions, which receives the contributions from the vector resonances due to chiral anomaly, is evaluated. This part of the electromagentic mass, which can contribute to the mass difference of $\pi^\pm-\pi^0$, is finite and as expected, is smaller than the contributions due to isospin symmetry breaking and electromagnetic chiral logs corrections, however, could be compared with the contribution from the short distance QCD., Comment: Revtex, 8 pages, no figures