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Ice crystal icing occurs in jet engine compressors, which can severely degrade jet engine performance. In this paper, two different numerical calculation methods, the Eulerian method and the Lagrangian method, were used to evaluate the dynamics, mass transfer, heat transfer, phase transition and trajectory of ice crystals. Then, we studied the effects of initial diameter, initial sphericity, initial temperature of ice crystal, and relative humidity of airflow on the phase transition and collection characteristics of ice crystal particles. Results indicate that the non-spherical characteristics of ice crystals have a significant impact on their impingement limits and collection characteristics. The collection coefficient of unmelted ice crystals is positively correlated with the initial particle diameter and sphericity, and negatively correlated with the initial particle temperature and the relative humidity of airflow. The melting rate of ice crystal particles on the impact surface increases exponentially with the initial diameter of the particles, linearly increases with the relative humidity of the airflow and initial temperature of the particles, and exponentially decreases with the sphericity of the particles. [ABSTRACT FROM AUTHOR]

This paper investigated the performance of a regenerative heat and mass exchanger (RHMX) for indirect evaporative cooling. A numerical model for RHMX was developed and validated with experimental data from the literature. Then, a data-driven model based on artificial neural network (ANN) algorithm was presented which was derived from the simulation results generated from the numerical model. The comparison between ANN prediction and experiment data showed good prediction accuracy. The average prediction error between the predicted and tested data was around 4% based on the air temperature change across the dry channel. With the data-driven model, parametric analyses were made to investigate the performance of the RHMX under different operating conditions. Finally, a design optimisation of the extraction air ratio was conducted under different ambient conditions. It was found that the optimal extraction air ratio decreased with the ambient temperature and/or relative humidity which ranged from 0.3 to 0.36. [ABSTRACT FROM AUTHOR]

• Up-to-data dew-point evaporative cooling techniques were comprehensively reviewed. • The recent applications in demand-side and supply-side were summarized. • Research limitations in temperature region and film distribution were discussed. • Future research directions with the use of renewable energy were highlighted. Dew-point evaporative cooling (DPEC) is a high-efficiency heat and mass transfer technique and has been widely used in various industries. The suitable and efficient application of this technology is helpful for energy conservation and can bring great benefits for the fulfillment of carbon–neutral development. In this paper, a comprehensive review of DPEC techniques was conducted through the introduction of its current applications and limitations. First, the theories behind DPEC together with the existing modelling methods and experimental tests were presented after a brief introduction of its research significance. Then, recent advances of DPEC techniques from both demand-side and supply-side applications were described in detail, such as Heating Ventilation Air Conditioning system, gas turbine and other special designs. The research gap between actual carbon–neutral applications and current techniques and potential future research directions were also discussed and finally, some conclusive remarks were outlined. This review concludes the current main characteristics of DPEC techniques and indicates the possible further investigation directions. The inadequate investigation in high temperature region or un-even distribution water film together with future renewable energy combination are highlighted, which is expected to guide the future development of dew-point evaporative coolers and serve the carbon–neutral strategies. [ABSTRACT FROM AUTHOR]

• The merit of humidified gas turbine cycle was investigated. • Two air saturator designs were considered for performance comparison. • Detailed heat and mass transfer analysis were employed for the air saturators. • Parametric studies were conducted under different operating conditions. • The Maisotsenko combustion turbine cycle offered higher energy efficiency. The urge for more energy-efficient power plant systems to relieve the energy crisis triggers the design for more advanced power cycles. The humidified gas turbine cycle is considered one of the potential choices, and the air saturator performance is critical to the energy merit of such kind of system. To understand more, the performances of humidified gas turbine cycles with two types of air saturator designs were compared in this study. Type 1 air saturator was a hybrid design which combined an indirect evaporative cooler with a Maisotsenko cycle while Type 2 was a conventional indirect evaporative cooler. Detailed heat and mass transfer analysis was taken into account in the air saturator modelling. Through system simulations, it was found that all the humidified gas turbine cycle systems offered higher system efficiencies than a simple gas turbine system with recuperator. Besides, parametric studies were conducted which highlighted the effects of system inlet air temperature, turbine inlet temperature, water injection rate, and part-load ratio on the performances of the different humidified gas turbine cycle designs. The employment of Type 1 air saturator offered 9.34% and 23.55% enhancement in the system efficiencies as compared to those using Type 2 air saturator under the design and 50% part-load ratio conditions respectively. This reinforced the benefit of applying Maisotsenko cycle to the air saturator design of humidified gas turbine cycle for the enhancement of system efficiency. [ABSTRACT FROM AUTHOR]

• The dimensionless factors of Maisotsenko cycle heat and mass exchanger were detected. • A dew-point effectiveness correlation was developed. • The mean absolute deviations of the proposed correlation were less than 6.75%. • The influence of dimensionless parameters was discussed. The Maisotsenko cycle heat and mass exchanger (HMX) has been proven to be a high-efficiency facility, which can be regarded as heat recovery to improve the efficiency of energy supply system or directly applied as an evaporative cooler. Many experimental tests and numerical simulations have been conducted to verify its performance and help to serve energy supply system simulation. However, it is impossible to conduct an experimental test over a wide range of working conditions and employing the numerical model for system simulation is also inconvenient. Therefore, the modelling of empirical correlations for the practical application of HMX becomes necessary. This paper conducts a detailed theoretical analysis of heat and mass transfer in HMX, and the influential dimensionless parameters on dew-point effectiveness were identified. A dew-point effectiveness correlation for HMX was proposed based on the detected parameters. The results indicated that the mean absolute deviations of the proposed correlation were 2.35% and 6.75% when compared with numerical simulation and experimental data respectively. The newly proposed correlation could be used directly to evaluate the performance of HMX or further benefit the system simulation when the HMX is used as heat recovery component. [ABSTRACT FROM AUTHOR]