Integration of Concentrating Solar Heat into Oil and Gas Operations for Increased Sustainability

According to Eni's mission to reach carbon neutrality in the countries where it operates, the development of renewable energy could be a key element in the company's strategy for evolving the business model towards a low carbon scenario. In this context, concentrating solar technology can provide a real solution in order to goal the carbon neutrality. Solar thermal energy could be an alternative source to the fossil fuel in industrial processes and also in the oil&gas sector, where the upstream operations (dewatering, stabilization, sweetening…) require substantial amounts of heat. Usually this heat is easily produced by combustion of natural gas available at the oil&gas site. Concentrating Solar Heat (CSH) technology allows to produce process heat by using specific collectors that concentrate the solar radiation onto a receiver where a heat transfer fluid is heated at medium/high temperature. A thermal energy storage can be added to the solar field to increase the solar fraction and reducing so the CO2 emissions. The fraction of thermal energy not covered by the CSH plant can be provided by a fossil source that acts as a back-up. With this in mind, a pre-feasibility study was carried out for the integration of a medium temperature(∼200-300°C) concentrating solar plant with or without a thermal storage system and a back-up gas heater in an oil&gas site located in North Africa. The solar heat partially replaces the duty necessary to the heat exchangers that heat the crude to guarantee the separation from water and best stabilization. Reflective areas of the solar field and total occupancy, thermal energy production during the year, solar multiple and preliminary evaluations of cost of investment are presented. Obviously, the reduction of CO2 emission increases with the solar fraction but the competitiveness and cost-effectiveness of the integration strongly depend on the local cost of natural gas, the presence of government incentives, CO2 credit tax, etc. In any case the proposed solution represents an important step towards energy transition.

Techno-economic assessment of the use of Linear Fresnel Solar Collectors for the supply of heat in traditional fruits and vegetable processing industries in Almeria’s province

This study presents a techno-economic assessment of the use of Linear Fresnel Solar Collectors for the heat supply in traditional fruits and vegetable processing industries in Almeria’s province. This assessment is justified by the high availability of solar radiation in the area under study, the evaluation of complementary energy self-consumption modalities, and the suitability of using local resources for the preservation and improvement of traditional productive activities. The work starts with an identification of the potential user’s needs and their location in the province. Afterward, the solar radiation resources have been estimated as they constitute one of the basic inputs for sizing the proposed systems. Together with the above, representative thermal demands have been considered and different configurations of commercial Linear Fresnel Solar Collector thermal plants aimed to contribute to solarize the analyzed productive processes have been designed and the corresponding techno-economic assessment have been undertaken. Main findings advance the profitability that can be achieved with this technology, reaching, after an optimized integration of the solar plant in the industrial process, a solar fraction between 66-82 % and payback periods of the investment between 6-12 years

Annual Thermal Performance of an Industrial Hybrid Direct–Indirect Solar Air Heating System for Drying Applications in Morelos-México

A theoretical–experimental annual analysis of a hybrid industrial direct–indirect solar air heating system performance for drying was conducted considering temperatures, useful energy Qu, efficiency η, and solar fraction SF. The direct solar air heating system located in Morelos, México, has flat-plate solar air collectors, and the indirect system has flat-plate solar water collectors, a thermal storage tank, a cross-flow fin, and a tube heat exchanger. A validated TRNSYS program modeled the process; the validation was carried out by comparing each component outlet temperature and useful energy with the respective experimental field data. The analysis considered annual usage over seven days a week, nine hours a day (from 09:00 to 18:00 h), and three operation modes. For the direct, indirect, and hybrid operation modes, the Qu values were 31.60, 55.19, and 75.18 MWh/yr; the annual η values were 0.44, 0.41, and 0.42; and the annual SF values were 0.45, and 0.73 for the indirect and hybrid mode, respectively. The hybridization of the direct–indirect solar air heating system increased annual performance by up to 58% in Qu and 42% in SF. The parametric analysis showed that a characteristic working nomogram of the hybrid system could be achieved, correlating the useful energy, efficiency, solar fraction, and operation temperature at a specified mass flow rate, and working temperature.

Integrating Novel Microchannel-Based Solar Collectors with a Water-to-Water Heat Pump for Cold-Climate Domestic Hot Water Supply, Including Related Solar Systems Comparisons

In Canada, more than 80% of energy in the residential sector is used for space heating and domestic hot water (DHW) production. This study aimed to model and compare the performance of four different systems, using solar energy as a renewable energy source for DHW production. A novel microchannel (MC) solar thermal collector and a microchannel-based hybrid photovoltaic/thermal collector (PVT) were fabricated (utilizing a microchannel heat exchanger in both cases), mathematical models were created, and performance was simulated in TRNSYS software. A water-to-water heat pump (HP) was integrated with these two collector-based solar systems, namely MCPVT-HP and MCST-HP, to improve the total solar fraction. System performance was then compared with that of a conventional solar-thermal-collector-based system and that of a PV-resistance (PV-R) system, using a monocrystalline PV collector. The heat pump was added to the systems to improve the systems’ efficiency and provide the required DHW temperatures when solar irradiance was insufficient. Comparisons were performed based on the temperature of the preheated water storage tank, the PV panel efficiency, overall system efficiency, and the achieved solar fraction. The microchannel PVT-heat pump (MCPVT-HP) system has the highest annual solar fraction among all the compared systems, at 76.7%. It was observed that this system had 10% to 35% higher solar fraction than the conventional single-tank solar-thermal-collector-based system during the wintertime in a cold climate. The performance of the two proposed MC-based systems is less sensitive than the two conventional systems to collector tilt angle in the range of 45 degrees to 90 degrees. If roof space is limited, the MCPVT-HP system is the best choice, as the MCPVT collector can perform effectively when mounted vertically on the facades of high-rise residential and commercial buildings. A comparison among five Canadian cities was also performed, and we found that direct beam radiation has a great effect on overall system solar faction.

Thermal Performance Prediction of Indoor Swimming Pool Solar Heating System Using Different Types of Flat-Plate Solar Collectors

The current study includes a theoretical study of the enfluence of different types of flat-plate solar collector on the solar fraction factor (ƒ) of a proposed solar heating system used for heating "alShaab Olympic Indoor Swimming Pool" located in Baghdad (Iraq) at a latitude of 33.32˚N. The swimming pool building has external dimensions of 95 m length, 51 m width, and 16.5 m height, it contains two pools, the first is for swimming with dimensions of (50 m * 21 m) with fixed depth of 1.8 m, the second is for diving with an irregular surface area of (351) m2 and with depth of 5 m. The Total thermal losses from the two pools to the pool hall and from the pool hall to the outdoor environment were calculated for four months of winter season (November, December, January and February) and a computer program was built using the MATLAB (R2008a) environment to solve the mathematical model equations in order to calculate the solar fraction facor (ƒ) of the proposed solar heating system at different solar collecting areas which are (2000,2500,3000,3500,4000,4500,5000,6000,7000,8000,9000,10000) m2 and at five different types of flat-plate solar collector which are (A: one cover black solar collector, B: one cover selective absorber solar collector, C: two cover black solar collector, D: two cover selective absorber solar collector, and E: pool absorber (PVC) solar collector). The results obtained showed that the highest values of solar fraction factor were obtained when using the solar collector type D, and the lowest values obtained when using the solar collector type E. The values of solar fraction factor (ƒ) of the proposed solar heating system, at solar collecting area of 10000m2 and at mass storage of water in the storage tank of 25 kg/m2 collecting area, for type D are 84.27 % for November, 72.74% for December, 69.4% for January, and 82.91% for February, and for type E are 56.14% for November, 41.15% for December, 37.17% for January, and 50.6% for February.

Design and Energy Analysis of a Solar Desiccant Evaporative Cooling System with Built-In Daily Energy Storage

Heat storage with thermochemical (TC) materials is a promising technology for solar energy storage. In this paper, a solar-driven desiccant evaporative cooling (DEC) system for air-conditioning is proposed, which converts solar heat energy into cooling with built-in daily storage. The system utilises thermochemical heat storage along with the DEC technology in a unique way. Magnesium Chloride (MgCl2·6H2O) has been used, which serves as both a desiccant and a thermochemical heat storage medium. The system has been designed for the subtropical climate of Lahore, Pakistan, for a bedroom with 8 h of cooling requirements during the night. MATLAB has been employed for modelling the system. The simulation results show that 57 kg of magnesium chloride is sufficient to meet 98.8% of cooling demand for the entire month of July at an elevated cooling requirement. It was found that the cooling output of the system increased with increasing heat exchanger effectiveness. The heat exchangers’ effectiveness was increased from 0.7 to 0.8, with the solar fraction increased from 70.4% to 82.44%. The cooled air supplied to the building meets the fresh air requirements for proper ventilation.

Investigation of a Solar Thermal Driven Refrigerated Warehouse in Tripoli-Libya using TRNSYS

This paper, illustrates a design and simulation of a solar powered absorption refrigeration system preserves food above freezing point. The main system is modified from a commercial conventional system located at Tajoura, Libya. The target is to design and operate the system at high solar fraction and efficiency. The simulation is performed by TRNSYS to evaluate the annual thermal performance of the solar system that consists of 50-kW absorption chiller producing cold for three refrigerated rooms. The model could be classified into two main parts; refrigeration load model and solar powered refrigeration system model. The results demonstrated that the optimum system achieves 51% solar fraction consists of 48 m2 of high performance evacuated tubes solar collectors and 5000-litre thermal storage tank, in order to power a 50-kW absorption chiller that offers cold for three refrigerated rooms of vegetables.

Validated TRNSYS Model for Solar Assisted Space Heating System

The present study involves a validated TRNSYS model for solar assisted space heating system as applied to a residential building in Jordan using new detailed radiation models of the TRNSYS 17.1 and geometric building model Trnsys3d for the Google SketchUp 3D drawing program. The annual heating load for a building (Solar House) which is located at the Royal Scienti?c Society (RS5) in Jordan is estimated under climatological conditions of Amman. The aim of this Paper is to compare measured thermal performance of the Solar House with that modeled using TRNSYS. The results showed that the annual measured space heating load for the building was 6,188 kWh while the heati.ng load for the modeled building was 6,391 kWh. Moreover, the measured solar fraction for the solar system was 50% while the modeled solar fraction was 55%. A comparison of modeled and measured data resulted in percentage mean absolute errors for solar energy for space heating, auxiliary heating and solar fraction of 13%, 7% and 10%, respectively. The validated model will be useful for long-term performance simulation under different weather and operating conditions.

Simulation Study of the Thermal Performance of MSF Desalination Unit Operating by Solar Vacuum Tube Collectors

The Center for Solar Energy Research and Studies (CSERS) has a good experience in operating and evaluating the thermal performance of small scale 5 m3/day Multi-Stage Flushing (MSF) desalination plant connected to solar pond according to the local weather conditions of Tajoura area. However, a new project has been suggested to run the desalination plant with vacuum tubes solar thermal collectors utilizing available technology and experience. In this study an attempt was made to make the best use of readily available components to operate the MSF desalination unit with field of solar thermal collectors. Several configurations of collectors and tank arrangements were designed and examined through the use of simulation software, TRNSYS. The study has shown that the layout-3 (two 500 litre storage tanks each of them connected to 9x5 vacuum tube collectors) gives the best performance with an annual solar fraction over 77% at load temperature of 70 °C with flow rate of 2500 lit/hr, and over 68% at load temperature of 80 °C for working condition of 8 hours daily. The study has also shown that running the desalination plant for 24 hours a day reduces the solar fraction of the solar collector field to 25%