Shiv Lal

Experimental, CFD simulation and parametric studies on modified solar chimney for building ventilation

The solar chimney is a passive solar system which can be used for enhance the natural ventilation and space conditioning of a building. A solar chimney design is modified and installed at CBRI Roorkee (29.87° N 77.88° E), India. A Computational fluid dynamics (CFD) software is used for prediction of velocity and temperature in Modified solar chimney (MSC) and evaluating the Air Change per hour (ACH), which is validated through experimental and theoretical counterpart and found a good agreement between them. From the result of thermal performance analysis, it is found that MSC generates 2.39–7.13 ACH in experimental room in month of May 2013, when outdoor solar radiation was in the range of 250–612 W/m2. Due to this ACH, the room temperature is dropped by 2–4°C as compared to reference room temperature. The parametric study shows that the optimum glass tilt angle estimated by 5 degree for highest performance consideration of MSC. The air gap is optimised by 60 mm and air gap to inlet opening height ratio is optimised by 0.2.

CFD Simulation Studies on Integrated Approach of Solar Chimney and Earth Air Tunnel Heat Exchanger for Building Space Conditioning

Individual studies on solar chimney and earth air tunnel heat exchanger have been carried out by various researchers but individual systems are not fulfilling the space heating and cooling demand of buildings. So, integrated approach of solar chimney and earth air heat exchanger has been studying in this communication. Computational fluid dynamics software is used for the modelling and simulation studies. The cooling effect is produced by 5.30-6.72 kW at 40°C ambient temperature and space heating is evaluated as 10.28-14.71 kW at 5°C ambient temperature and 400-1000 W/m2 16 solar radiations. And it is sufficient heating and cooling for buildings at average solar irradiance. The SC-EATHE integrated system approach produced 18 37% higher heating and cooling effect than the EATHE alone system.

CFD Simulation Studies for Vertical Temperature Profile, Pitch Optimisation and Parametric Study of Borehole Heat Exchanger

In this communication, simulation studies of a borehole heat exchanger are worked out through computational fluid dynamics (CFD) software. A two dimensional (k-e) realizable turbulent model with standard wall function is used to evaluate the temperature variation along with depth of BHE, pitch optimization and to determine the effect of two dimensionless parameters as ratio of pitch to borehole diameter and ratio of borehole to pipe diameter. The predicted results are validated through experimental data; and statistical assessment shows a good agreement between simulated and experimental results. The tube air temperature is proportional to depth in cooling mode and BHE can decrease the temperature of air by 13-14°C when ambient temperature observed by 41°C. The optimised pitch for 8 inch borehole and 2 inch diameter U-tube is found to be 4 inch, however two U-tubes are recommended for enhanced performance. The effective borehole to tube diameter ratio is estimated by 4. The BHE system can be used for heating and cooling of buildings it is a feasible solution for sustainable development.

Thermal performance prediction and energy conservation potential of earth air tunnel heat exchanger for thermal comfort in building

In this communication, thermal performance of building integrated “Earth Air Tunnel Heat Exchanger” (EATHE) has been studied for a composite climate of Delhi. Mathematical model and building thermal simulation software (Energy Plus) are used for prediction of indoor air temperatures. The predicted results are validated through experimental results. Energy conservation potential both for heating and cooling of EATHE has been evaluated for winter and summer months in a specific year. Quantitative assessment of CO2 mitigation has also been computed. It is observed that Coefficient of performance (COP) of EATHE is found between 6.3–13 during summer and 6.8–9.5 during winter season. The maximum drop in air temperature across the earth air tunnel is found to be 8.7 °C with air velocity of 2.69 m/s during peak summer and during winter season the room air temperature is raised by 5–7 °C. On the other hand, the system is capable of maintaining room temperature in the range of 27–30 °C during peak summer when outdo...

Performance evaluation, energy conservation potential, and parametric study of borehole heat exchanger for space cooling in building

A building integrated Borehole Heat Exchanger (BHE) has been designed and installed at Central Building Research Institute, Roorkee (29.87°N 77.88°E) India. The thermal performance and energy conservation potential (cooling potential) of installed BHE have been evaluated during summer months in the year 2013. The parametric study has also been done for its maximum performance. Quantitative assessment of CO2 mitigation has also been computed. The constant BHE water temperature (approximately 25 °C) witnessed the transferring of heat from air to water and vice-versa. It is found that the air temperature is reduced by 8–13 °C during summer season at air velocity of 18.9 m/s from the inlet of the BHE (exit of blower), whereas outdoor temperature was recorded as 35–39 °C. This system is capable of maintaining room temperature between 26 and 30 °C during peak summer season. The cooling capacity is evaluated between 150 and 180 kW h. BHE integrated with building can significantly reduce the 39836.25 kW h of elec...

A case study on solar chimney-assisted ventilation for residential building in India

Purpose – The ventilation and air-conditioning systems consume the highest energy in the building sector. The proper ventilation in residential buildings through the passive solar systems can substantially reduce the energy consumption in building sector. The paper aims to identify the application of wind shaft as a solar chimney, a passive ventilation system and evaluated the performance of the system. Design/methodology/approach – The paper investigated the performance of the solar chimney with size, absorber area 9.76 m2 and height 4.57 m, based on experimental data recorded in the city, Kota (25°10N, 75°52E), India. Solar data were recorded using the state of the art weather station situated very closer to the residence. The air velocity and temperatures in the chimney and in the building are recorded in data logger. A simple mathematical model was used for the evaluation of the air change per hour (ACH) in the residential building. Findings – From the analysis of weather data, it was found that the a...