A variable refrigerant flow integrated stratum ventilation (VRF-SV) system was proposed as an energy efficient substitute for conventional central cooling systems for buildings. The novel system provided conditioned air to enclosed spaces with high indoor air quality and thermal comfort. This study investigated the effects of different types of ASTDs on the performance of the VRF-SV hybrid system. The performance was experimentally evaluated with five air terminal types, including bar grille, double deflection grille, jet slot, perforated and drum louver diffusers. The evaluation was carried out using standard indices: temperature and velocity distribution, airflow pattern, effective draft temperature (EDT), air distribution performance index (ADPI), thermal sensation vote and comfort feedback survey. The results indicated that the ASTD type had a significant impact on airflow pattern. Furthermore, the bar grille diffuser provided the occupants with greater thermal comfort and acceptable indoor environment. Almost all the EDT values determined in the breathing zone in the case with bar grille diffuser found under the satisfactory range, i.e., −1.2 < K < 1.2. Based on these values, the ADPI for bar grille diffuser was calculated as 92.8%. Thus, the bar grille diffuser is recommended to be installed with the VRF-SV hybrid system in buildings.

In this paper, the performance of an integrated variable refrigerant flow (VRF) system with the stratum ventilation (SV) system was numerically examined and compared with the experimental measurements in terms of temperature distribution and airflow patterns. In total six different configurations were designed and analyzed. The results suggest that configuration 5 was greatly satisfied the airflow movement needs. The positive thermal gradient with a modest airflow velocity (< 0.8 m/s) was setup in the entire breathing zone. The indoor temperature in the range of 20°C–22°C was seen throughout the occupied space, except for some places near the walls. Furthermore, a very strong airflow throw from the SV supply terminals was observed with the recommended value of face velocity. Hence, the VRF-SV hybrid system could achieve a better thermal comfort (TC) and indoor air quality (IAQ) in large ACMV applications.

Heat exchangers play a vital important role in industries and processing equipment’s. Among them, the double pipe heat exchanger facilitates the exchange of heat between two fluids through surface tubes. This study aimed to investigate various thermal performance parameters of baseline water and Aluminum oxide nanofluid at various volume concentrations and flow rates. The results were compared between baseline water and Aluminum oxide nanofluid using a test rig at the temperature range of 60 °C for industrial applications. The nanofluid sample was prepared by adding very small-sized (20nm) Al2O3 nanoparticles in the baseline water within the range of 0.10% to 0.175% using a standard two step method for the sterilization process. The nanoparticle and baseline water were under set by a hot plate mechanical stirrer for approximately 2 hours to ensure the proper dispersion before the tests, rendering the nanofluid stable for 12 hours. The Laminar-Transition flow double pipe heat exchanger (test rig) operated at flow rates ranging from 1.6×10-5-3.3×10-5 m3/sec (1-2 LPM) within the range of Reynolds number from 1700 to 3400 at volume concentration of 0.10% to 0.175% Moreover, an addition of 0.175% of Al2O3 nanoparticle in the baseline improved the average heat transfer coefficient from 140% to 155%, thermal conductivity of 21.6% and, 5.94% efficiency in counter flow direction and also showed higher friction factor i.e. 2.81% than baseline water. The results suggest that Al2O3-nanofluid at 0.175% could function very well as working fluid for industrial requirements compared to the conventional baseline water.

An environmentally friendly and energy-secure approach is to recycle waste cooking oil (WCO) for use in diesel engines. In place of costly pre-heating and trans-esterification, diesel-WCO-alcohol ternary blends offer a simple and affordable way to use both a bio-component and a recycled component to substitute diesel and lower the viscosity of WCO partially. This investigation tested three fuel samples: 20% waste cooking oil, 65% DF, and 15% n-pentanol; diesel fuel, which served as the reference; and 5% waste cooking oil and 95% DF. The 200-hour endurance test was performed on the single-cylinder CI engine. An atomic absorption spectrophotometer equipped with hollow cathode lamps for every element was used to quantify the engine wear debris, and scanning electron microscopy and energy-dispersive X-ray spectroscopy procedures were employed to analyze the elements and measure deposit accumulations. Furthermore, temperatures at and around the injector tip caused by modern diesel injection systems may result in incredibly persistent deposits. After prolonged use, some fuels can damage the engine itself, generate excessive carbon and lacquer buildup, and make an engine operate less efficiently. The proportion of carbon layer on injector surfaces for DF, DF95WCO5, and DF65WCO20Pe15 is 32.54%, 56.17%, and 27.58%, respectively. In this experimental investigation, the fuel DF65WCO20Pe15 showed minimal injector deposit buildup.