Thermal Performance Improvement of Solar Parabolic Dish System Using Modified Spiral Coil Tubular Receiver

The present research intends to design an efficient receiver for solar thermal applications with a solar dish concentrator system. Thermal and dynamic analysis is carried out for different convolutions of a spiral coil, and experiments are performed for testing the modified absorber. Experimental results are validated for the spiral absorber with numerical results. Three receivers of different numbers of convolutions are analyzed, and simulation steps are performed for these receivers to make improvements in the system efficiency. Finally, 5 convolutions of a spiral coil tubular absorber are taken for the modified design of the system. Absorber position for every spiral convolution is kept at the focus of the concentrated solar dish collector to achieve maximum efficiency. Material used for the reflective surface is anodized aluminum and copper for the absorber. The diameter of the aperture for the parabolic dish collector is 1.4 m. The maximum absorber temperature for May month comes out to be 296°C, and the maximum working fluid outlet temperature is found to be 294.2°C which is near to simulating temperature of 289.59°C and 288.15°C, respectively. This innovative design of the absorber consists of a feature of a 5 mm extension to the spiral tube at the exit and entry; hence, the turbulence effect could be overcome. Experimental thermal efficiency was found the highest (i.e., η th max = 75.98 % ) for May. This work emphasizes on improving thermal performance by obtaining optimum absorber size using convolution strategy. Investigation of 5 convolutions of spiral coil tubular absorber with extended ends for obtaining optimum performance than existing work is the superiority of this work.

Prediction of Focal Image for Solar Parabolic Dish Concentrator With Square Facets – An Analytical Model

Solar parabolic dish concentrator is one of the high-temperature applications of more than 400 °C for thermal and electrical power generation. In the solar parabolic dish concentrator, the arrangement of reflectors over the surface area is the significant factor for effective concentration of solar radiation. Also, focal image is one of the most influencing parameters in the design of receiver. Among the various reflectors, the square shaped reflectors (facets) are comparatively effective in converging the incoming radiations to attain better focal image. In this regard, an attempt has been made to predict the focal image diameter of a solar parabolic dish concentrator with a square facet of different influencing parameters using a novel mathematical model. The influencing parameters considered for the study are aperture diameter, rim angle, and facet length of the dish concentrator. Based on the proposed model, the focal image dimension and aperture area of a solar parabolic dish concentrator with square facets can be predicted accurately for efficient design of a solar parabolic dish collector system. Finally, the proposed model is validated with the experimentally obtained focal image diameter and it is observed that the predicted result is in good agreement with the experimental one. Thus, the proposed model can be effectively used for the design of parabolic dish system for sustainable development.

Dual axis solar tracking system for a parabolic dish CPU water heater

The solar parabolic dish water heater is highly efficient but has limited hours of work only when sunlight is perpendicular to its surface. Therefore, this work aims to continue the work of the solar parabolic dish in the daytime using a dual tracking system, depending on the geographic location of the system (longitude and latitude angles) and using the C # programming language. To verify the effect of the dual-axis solar tracking system, the current study considered two types of solar parabolic dishes, the first was fixed, and the second was a rotating dish (by the dual tracking system). It was observed that the water temperature at the outlet of the tracking type solar water heater is 22% higher than that for the fixed dish type; this means that the proposed system has improved the temperature of water in the heat exchanger. Therefore, the highest water temperature value of about 51.4ffiC was at the outlet of the heat exchanger for the tracking type at 1:00 pm, while the temperature recorded for the fixed type was about 46.1ffiC. The highest energy gained from the solar heating system was at 1:00 pm for both types, which was about 76.9 W from the tracking type and 54.7 W from the fixed type. It was also observed that in the fixed dish type, most energy losses occurred during the daytime, while for the tracer of the dish type, useful energy was gained during most of the sunny working hours depending on the solar radiation intensity.

Technical feasibility on reception of VHRR signals from Kalpana-1 satellite in the event of contingency with the existing operational ground receiving system

National Satellite Meteorological Center (NSMC), of India Meteorological Department is performing the vital role of receiving signals of meteorological data transmitted by KALPANA-1/INSAT series of national satellites and processing the data to generate various meteorological products for monitoring meteorological, environmental and climatological conditions. The satellite signals are currently being received through a 7.5 m diameter parabolic dish antenna installed at INSAT Earth Station of IMD located at Mausam Bhawan Complex, New Delhi. In this study an attempt has been made to receive and process the VHRR signals of KALPANA-1 through a smaller (3.8m) diameter parabolic dish antenna available at earth station .The link calculations have been made to show extra 2 db margin what is theoretically required and it will be sufficient for image capturing. We had also compared the result with existing 7.5m diameter antenna and observe that quality of satellite pictures received with 3.8m diameter antenna are also equally good. The purpose of this study is to keep in operational readiness a backup antenna for the reception of KALPANA-1 in the event of any unforseen contingency with the existing 7.5m diameter parabolic dish antenna, using the existing infrastructure of IMD.

Integration of a Solar Parabolic Dish Collector with a Small-Scale Multi-Stage Flash Desalination Unit: Experimental Evaluation, Exergy and Economic Analyses

In this study, a small-scale two-stage multi-stage flash (MSF) desalination unit equipped with a vacuum pump and a solar parabolic collector (PDC) with a conical cavity receiver were integrated. To eliminate the need for heat exchangers, a water circulation circuit was designed in a way that the saline feedwater could directly flow through the receiver of the PDC. The system’s performance was examined during six days in July 2020, from 10:00 a.m. to 3:00 p.m., under two distinct scenarios of the MSF desalination operation under the vacuum (−10 kPa) and atmospheric pressure by considering three saline feedwater water flow rates of 0.7, 1 and 1.3 L/min. Furthermore, the performance of the solar PDC-MSF desalination plant was evaluated by conducting energy and exergy analyses. The results indicated that the intensity of solar radiation, which directly affects the top brine temperature (TBT), and the values of the saline feedwater flow rate have the most impact on productivity. The maximum productivity of 3.22 L per 5 h in a day was obtained when the temperature and saline feedwater flow rate were 94.25 °C (at the maximum solar radiation of 1015.3 W/m2) and 0.7 L/min, respectively, and the MSF was under vacuum pressure. Additionally, it was found that increasing the feedwater flow rate from 0.7 to 1.3 L/min reduces distillate production by 76.4% while applying the vacuum improves the productivity by about 34% at feedwater flow rate of 0.7 L/min. The exergy efficiency of the MSF unit was obtained as 0.07% with the highest share of exergy destruction in stages. The quality parameters of the produced distillate including pH, TDS, EC and DO were measured, ensuring they lie within the standard range for drinking water. Moreover, the cost of freshwater produced by the MSF plant varied from 37 US$/m3 to 1.5 US$/m3 when the treatment capacity increased to 8000 L/day.

Numerical study of Flow patterns and performance of a coupled cavity-dish system under different focal lengths

The effectiveness of the parabolic dish system (PDS) is greatly affected by the heat losses associated with high temperatures. The complexity of flow and temperature patterns in and around the cavity receiver makes it a challenging task to determine the convective heat loss from the cavity. Various studies have been carried out to determine the convection heat losses from isolated cavities of different shapes. In the presence of dish structure, the free stream wind may affect the stability of structure and the heat losses from the PDS. In this study, effect of focal length on the performance of the coupled cavity-dish system was analyzed using numerical simulations. The loading and the convective heat loss from the cavity were examined with three different cavity positions and different operating conditions in the presence of the dish. The results showed that the shallow dish experienced higher local air velocities near the cavity receiver than in the case of the deep dish. It was concluded that the heat loss is a stronger function of tilt angle rather than focal length, and in essence, the heat losses due to variation of this are negligible.