PERFORMANCE ASSESSMENT OF A LARGE INTERNAL COMBUSTION ENGINE DUE TO INLET AIR COOLING AND DEHUMIDIFICATION: GT-POWER SOFTWARE SIMULATION

Large internal combustion engines (ICEs) performance is limited by knocking phenomenon due to harsh ambient conditions such as hot temperature and excessive humidity. The performance of these engines can be enhanced by cooling and dehumidifying the inlet air on turbocharger upstream under safe operation conditions through a cooling coil heat exchanger, hence, increasing the power output as well as reducing the brake specific fuel consumption and pollutant specific emissions. Analysis have been performed in the GT-POWER software through a 1-D thermodynamic modelling of the Wärtsilä W20V34SG engine, making it possible to verify the influence of cooled and dehumidified ambient air, considering a temperature range from 9.5°C (282.7 K) to 15.5°C (288.7 K), while keeping 1 bar for pressure and relative humidity of 100%. Furthermore, the brake mean effective pressure (BMEP) has been set from 20 to 23.45 bar with a step of 1.15 bar. Such simulations are aimed to find the maximum air temperature at the cooling coil outlet in which the average of maximum cylinder pressures does not exceed the safety limit pressure of 186 bar while maintaining control on the wastegate valve. As a result, it was possible to evaluate that the maximum temperature to be chosen, under the conditions already mentioned, should be lower than 13.8°C (287 K).

Transient Thermal Analysis of a Solar-Assisted AHU by Focusing on Heat Recovery and Nanoparticles: Jeddah Climate Zone

In the Jeddah climate region, a lot of energy is assigned to the air handling unit (AHU) sector, which should be reduced by using energy-efficient solutions. As the air passes through the cooling coil, a lot of energy is consumed to reduce the temperature along with humidity so that if the air is precooled in the previous stages, energy consumption in this energy-intensive section will be diminished. Using the coldness of the return air in the heat recovery unit (HRU), the incoming air is precooled. Based on the thermodynamic calculations, in June, July, and August, the cooling coil power demand reduces by 11.6, 13.3, and 12%, respectively. In summer, owing to using HRU, an energy-saving by 76.08 MWh is achieved (12.34% reduction in energy demand). By the incorporation of the solar collectors in the AHU, heating coil demand diminishes by 1,206, 1,399, and 1,367 kWh in June, July, and August, respectively. To improve the solar-assisted AHU effectiveness, the MWCNT nanoparticles are injected into the collectors, and it is found that the saving-energy capability improves by 17.7% using MWCNT-water at 0.1 vol.%.

DEVELOPMENT OF OFF-DESIGN TURBOCHARGER MODELLING COMBINED WITH 1-D ENGINE MODEL

The present work aims to carry out an off-design turbocharger modellingpowered by exhaust gases from a Wärtsilä 20V34SG engine. First of all, 1-D engine model was already developed in GT-Power software whileconsidering a thermodynamic turbocharger modelling with constantisentropic efficiencies. Secondly, by using the results from 1-D enginemodel, the off-design turbocharger modelling is calibrated separately inEES software, taking into account compressible assumption, trianglevelocities and geometric dimensions. The case study is derived from a R&Dproject (ANEEL PD-06483-0318/2018) that targets to cool and dehumidifythe intake air at compressor’s upstream through a cooling coil, therebyallowing engine’s operation at reduced knocking conditions. The brakemean effective pressure (BMEP) is varied in the range of 20 to 23.45 bar,corresponding to brake power from 8.7 to 10.2 MW, respectively. With theoff-design turbocharger modelling it is possible to analyze its operationalbehavior under higher BMEP, hence, allowing to predict some importantparameters. The results showed that the turbocharger is operating within themanufacturer’s limit for BMEP of 23.45 bar, presenting total-to-staticisentropic efficiencies of 0.81 and 0.784 for compressor and turbine,respectively, rotational speed around 28135 RPM, pressure ratio atcompressor of 4.567 and maintaining control on waste-gate valve.

Development and performance analysis of a PCM based cooling fan for hot climate of Bangladesh

In hot climatic regions, some kind of cooling system is necessary to avoid warmth and humidity. Many of the available cooling systems are not economic and sustainable. In this study, sustainable and feasible space/room cooling systems have been experimentally analyzed. A solar operated cooling system with two options have been designed and their performances are compared. Phase Change Material (PCM) is proposed to store thermal energy instead of a costly battery. A 1200-watt compressor and fin-type condenser are used to construct the vapor compression system. When the incoming air is passed through the cooling coil, it gets cool. For this cooling coil, 50 feet copper tube is used. The front side copper tube diameter of the fan is 3/8 inch and the backside tube diameter is 1/2 inch. It took about 35 minutes and 5 minutes to minimize the room temperature at the desired level in the case of the stand fan and duct fan, respectively. Furthermore, the stand fan and duct fan systems reduced 3 ℃ and 6 ℃ of the outside temperature, respectively.

Novel Solar driven Cooling System Integrated with Solar Still System

Novel integrated solar cooling and solar distillation system is introduced to meet the high cooling and fresh water demands in hot and arid regions such as Qatar. The system is composed of a solardriven ejector cooling system coupled with a single-slope solar still. The introduced novel system is the first study that integrates two solar systems for cooling and water production with outputs significantly higher than any existing system. The results show that the productivity of the solar still is improved by enhancing the evaporation rate (using heating coil) and by increasing the condensation rate (using cooling coil). Simultaneously, this improved the COP of the ejector system by increasing its entrainment ratio with a slight increase in the required solar collector area. The performance of four different scenarios of integration between the proposed cooling and distillation systems is investigated. The results showed that the productivity of the still is five times higher than that of the conventional solar still. The annual produced water considering the hourly variation of the radiant flux was 5067 kg/year, which is 5.7 times more than the conventional systems. The estimated cost of one-liter distilled water per 1 m2 area of the present solar still is $0.04, which is only 18% of the water cost of other still technologies.

Empirical Modeling of Direct Expansion (DX) Cooling System for Multiple Research Use Cases

This study provides a general procedure to generate a direct expansion (DX) cooling coil system for a roof top unit (RTU), which is a typical heating ventilation and air-conditioning (HVAC) system for commercial buildings in the United States. Experimental data from a full-scale unoccupied 2-story commercial building is used for the HVAC modeling. The regression for identifying the model coefficients was carried out with multiple stages, and the results were validated with measured data. The model’s applicability was evaluated with multiple case studies, including a building energy simulation (BES) program validation, model-based predictive control (MPC), and fault diagnostics and detection (FDD).