Search results for " Chemical exergy"
showing 5 items of 5 documents
On the reliability of thermoeconomic diagnosis of fouled evaporators: assessing the influence of geometries, operating conditions and reference state
2015
Thermoeconomic diagnosis of refrigeration systems is a pioneeristic approach, which has been proven to achieve good performances (under favorable conditions) for the detection of specific faults such as condenser and evaporator fouling and compressor valve leakage. In this paper the sensitivity of performance in detecting fouled Direct Expansion (DX) coils is investigated; the examined parameters are the temperature and relative humidity of coil inlet air and the sensible/latent heat ratio of the coil (varied by considering different numbers of rows). As the thermoeconomic model requires splitting the specific exergy of cooling air into “mechanical”, “thermal” and “chemical” fractions, and …
Exergy analysis of electrodialysis for water desalination: Influence of irreversibility sources
2022
The increasing freshwater demand is pushing the development and adoption of desalination technologies. In this framework, electrodialysis has a consolidated role in brackish water desalination, but to make it competitive with other technologies for the desalination of more concentrated solutions (e.g., seawater), the specific energy consumption should be reduced. Exergy analysis provides a useful tool for determining the contribution of each thermodynamic inefficiencies on the process efficiency and the specific energy consumption. In this regard, this paper presents an exergy analysis of the electrodialysis process. A 1-D model is used for evaluating the performance of industrial-scale sys…
Assessing the Robustness of Thermoeconomic Diagnosis of Fouled Evaporators: Sensitivity Analysis of the Exergetic Performance of Direct Expansion Coi…
2016
Thermoeconomic diagnosis of refrigeration systems is a pioneering approach to the diagnosis of malfunctions, which has been recently proven to achieve good performances for the detection of specific faults. Being an exergy-based diagnostic technique, its performance is influenced by the trends of exergy functions in the “design” and “abnormal” conditions. In this paper the sensitivity of performance of thermoeconomic diagnosis in detecting a fouled direct expansion coil and quantifying the additional consumption it induces is investigated; this fault is critical due to the simultaneous air cooling and dehumidification occurring in the coil, that induce variations in both the chemical and th…
Exergy analysis of reverse electrodialysis
2018
Abstract Reverse electrodialysis in closed loop configurations is a promising membrane technology in the energy conversion and storage fields. One of the main advantages of closed-loop reverse electrodialysis is the possibility of using a wide range of operating concentrations, flow rates and different salts for generating the salinity gradient. In this work, an original exergy analysis of the reverse electrodialysis process was carried out in order to investigate reverse electrodialysis performance in terms of energetic and exergetic efficiency parameters in a wide range of operating conditions. A mono-dimensional model of the reverse electrodialysis process was developed, in which all sou…
Exergy Analysis of Reverse Electrodialysis Heat Engine with Multi-Effect Distillation Regeneration Stage
2018
The increasing worldwide energy demand is rising the interest on alternative power production technologies based on renewable and emission-free energy sources. In this regard, the closed-loop reverse electrodialysis heat engine (RED-HE) is one of the most promising technologies currently under investigation. This technology produces electric power by harvesting the salinity gradient energy released from the controlled mixing of two artificial salt solutions with different concentrations. Low-grade heat (T < 100 °C), derived from any industrial process is used in a multi-effect distillation (MED) unit to restore the initial salinity gradient of the solutions. In this work, a comprehensive…