Research on a Solar Hybrid Trigeneration System Based on Exergy and Exergoenvironmental Assessments

The environmental performance of a combined cooling, heating, and power system is analyzed in this study at a component-level using a SPECO-based exergoenvironmental analysis. The engine consumes natural gas and produces 168.6 kW net power. The waste heat is recovered by a LiBr-H2O absorption chiller and a heat exchanger, which are used for cooling and heating purposes. The energy system is assisted by a solar field. An environmental Life Cycle Assessment quantifies the environmental impacts of the system, and these data are combined with exergy evaluations. The highest total environmental impact rate, 23,740.16 mPt/h, is related to the internal combustion engine, of which pollutant formation is the primary source of environmental impact. Compared with a non-renewable energy system, the solar-assisted trigeneration system decreased the environmental impact per exergy unit of chilled water by 10.99%. Exergoenvironmental performance can be further improved by enhancing the exergy efficiency of the solution pump and high-pressure generator (HG), and by employing a treatment to remove nitrogen oxides in the reciprocating engine.

Feasibility Study of Bio-fuel As a Sustainable Product of Biomass: An Overview of Its Fundamentals, Application and Environmental Impact

The energy crisis and ecological disasters have become a critical problem in recent decades. The human activities through industrial operations increase emissions and other pollutant particulates in the world as a result of steady patronage on fossil feedstock. Several experiments were performed to identify an alternative fuel meeting the rising energy demand. Biomass (bio-fuel) has recently been developed as an economical fuel, environmentally friendly resource, renewable and sustainable fuel. Approximately 350 crop plants were evaluated and some of them could be considered as suitable alternative diesel engine fuels. To increase the bio-fuel quantity globally, apart from crops, other biomaterial sources are considered potential in biofuel production. It was shown that the properties of biofuel combustion are identical to fossil. In the experimental combustion of biodiesel blends, higher ignition pressure and temperature, shorter ignition delay, and higher peak release were recorded. This paper is a literature review on the need for biofuels as a global renewable fuel resource and aims to explain the characteristics of combustion and pollutant formation in the application of biofuels. The study also stated the resources, the use of biogas and its emission impact in flameless combustion mode. With holistic adoption of biomass source of fuel together with the modern conversion techniques, issues from fuel emissions will be mitigated.

Improvement in Modeling of OH and HO2 Radical Concentrations during Toluene and Xylene Oxidation with RACM2 Using MCM/GECKO-A

Due to their major role in atmospheric chemistry and secondary pollutant formation such as ozone or secondary organic aerosols, an accurate representation of OH and HO2 (HOX) radicals in air quality models is essential. Air quality models use simplified mechanisms to represent atmospheric chemistry and interactions between HOX and organic compounds. In this work, HOX concentrations during the oxidation of toluene and xylene within the Regional Atmospheric Chemistry Mechanism (RACM2) are improved using a deterministic–near-explicit mechanism based on the Master Chemical Mechanism (MCM) and the generator of explicit chemistry and kinetics of organics in the atmosphere (GECKO-A). Flow tube toluene oxidation experiments are first simulated with RACM2 and MCM/GECKO-A. RACM2, which is a simplified mechanism, is then modified to better reproduce the HOX concentration evolution simulated by MCM/GECKO-A. In total, 12 reactions of the oxidation mechanism of toluene and xylene are updated, making OH simulated by RACM2 up to 70% more comparable to the comprehensive MCM/GECKO-A model for chamber oxidation simulations.