Mathematical modelling and simulation of the dehumidifier for the tropical region of Malaysia
In this paper, mathematical model for an adiabatic dehumidifier of liquid desiccant air conditioning system is presented. Regression approach is used to generate the mathematical relation between enthalpy and humidity ratio. Flow-pattern between air & desiccant mainly affects the performance of adiabatic dehumidifier therefore to get proper dehumidification counter-flow configuration is considered as previous studies show that counter-flow direction of air to desiccant has better dehumidification results. For validation, results of present study were compared with those of numerical and analytical results of previous studies, and the agreement was found to be quite satisfactory. The developed mathematical model is then used to study the performance analyses of adiabatic-dehumidifier for the tropical region of Malaysia. Analyses are made for the week having very high range of humidity ratio (18 - 19.5 g/kg). The main concern of the current article is given on moisture removal from the ambient air according to thermal comfort-zone.
Internal Model Control (IMC)-Based Active and Reactive Power Control of Brushless Double-Fed Induction Generator with Notch Filter
The increase in demand for electricity and, in particular, green energy has put renewable energy systems at the focal point of energy policy worldwide. The higher reliability of brushless doubly fed induction generators (BDFIGs) makes them suitable for offshore and remote wind energy generation (WEG) applications. Besides, controlling the active and reactive powers in an electrical power system is critical for optimal voltage regulation, reduced power losses, and enhanced utilization of installed equipment. However, the existing literature on BDFIG’s active and reactive power control highlights the poor dynamic response and high transients with harmonic generation during inductive load insertion. It is because the Ziegler technique was employed to select PI gains, and the instantaneous reactive power theory was used to mitigate harmonics. Considering that, this paper proposes a vector control (VC) method for BDFIGs in wind turbines, in which the proportional-integral (PI) gains for internal model control (IMC) are optimized to improve the dynamic response of the active and reactive power during inductive load insertion. The proposed method reduces the complexity, time consumption, and uncertainty in making the optimal choice. In addition, to reduce a double fundamental frequency component to the point-of-common-coupling (PCC) voltage, the excellent characteristics of the notch filter are utilized in the grid-side converter (GSC)-based vector control scheme. The simulation results in MATLAB/Simulink show that the proposed IMC-based vector control scheme with a notch filter provides satisfactory results with a minimum peak value compared to existing techniques.
Psychometric technoeconomic assessment and parametric studies of vapor-compression and solid/liquid desiccant hybrid solar space conditioning systems
Abstract This communication presents some studies on hybrid vapor-compression (V-C) and solid/liquid desiccant solar air-conditioning systems. Desiccants are used to bring the humidity within the comfort range by partially converting the latent heat load (LHL) into sensible heat load and then meeting this load with conventional V-C cycle. In both the options of hybrid systems consisting of vapor-compression and solid/liquid desiccant cycles, heat rejected from the condenser of the V-C cycle is used to regenerate the desiccants to improve the coefficient of performance (COP) of the systems. A thermodynamic assessment and technoeconomic feasibility study of hybrid V-C and solid/liquid desiccant solar air-conditioning systems have been presented. It is found that a hybrid system with desiccant cycle is more promising under high latent heat load and higher ambient humidity conditions and significant energy saving can be achieved over standard V-C cooling systems.