• Energy Research

Concentrating solar power plant will be a key component of the future energy systems in which the share of renewable energy is extremely high. A major challenge of this technology is, however, its intermittent power output, slowing down its rate of implementation in the global energy matrix. As such, waste incineration is a popular technology in the developed countries as a smart measure for the disposal of municipal waste and generating free energy. In this study, a hybrid configuration of a concentrating solar power plant accompanied with a waste incineration unit is proposed. In the proposed system, the waste incinerator offers a variable heating duty in order to regulate the power output of the concentrating solar power plant. The hybrid plant is designed for a case study in Denmark and is thermodynamically analyzed. The results of the simulations are presented and discussed. It is shown that the hybrid system can pave the bed for increasing the share of solar thermal power and bringing more waste incinerators to the electricity market. A 10 MWe hybrid power plant may prevent up to 8000 tonnes of carbon dioxide equivalent emission per month. The overall efficiency of the hybrid system is expected to be 24%.

Abstract The effect of vortex generator parameters (Cold orifice angle, Cold orifice diameter and Nozzle area) on vortex tube performance is investigated experimentally. Vortex tube is connected to a natural gas pipeline with constant pressure of 4 bars. To improve vortex tube efficiency, six generators with different cold orifice angle, five generators with different cold orifice diameter and three generators with different nozzle area are studied for each experiment part. Results show variation of nozzle area has no effect on optimum cold mass fraction while cold mass angle and cold mass diameter move this point. Increment in cold orifice diameter increases optimum cold mass fraction and decreases cold temperature. As the angle of cold orifice increases, more mass flow passes through cold outlet and optimum cold mass fraction also increases. The expansion of the gas in the diffuser type cold orifice is investigated as the dominating reason for the different vortex tube performance. These mentioned designing parameters of vortex generator affect the flow pattern and efficiency of vortex tube as a consequence. For cold orifice angle of 4.1°, cold orifice ratio of 0.64 and nozzle area ratio of 0.14, highest efficiency is achieved.

Renewable cooling via absorption chillers being supplied by various green heat technologies such as solar collectors has been widely studied in the literature, but it is still challenging to get positive economic outcomes from such systems due to the large expenses of solar thermal systems. This study offers the use of a new generation of solar collectors, so-called eccentric reflective solar collectors, for driving single-effect absorption chillers and thereby reducing the levelized cost of cooling. This article develops the most optimal design of this system (based on several different scenarios) using multi-objective optimization techniques and employs them for a case study in Brazil to assess its proficiency compared to conventional solar-driven cooling methods. For making the benchmarking analyses fair, the conventional system is also rigorously optimized in terms of design and operation features. The results show that the eccentric solar collector would enhance the cost-effectiveness by 29%. In addition, using optimally sized storage units would be necessary to get acceptable economic performance from the system, no matter which collector type is used. For the case study, at the optimal sizing and operating conditions, the levelized cost of cooling will be 124 USD/MWh and an emission level of 18.97 kgCO2/MWh.

In the present study, a novel design of large-scale biomass-based heat-driven building cooling system is proposed and investigated for different regions of India. The study is enriched by a thorough benchmarking analysis of various scenarios (24 scenarios in total) for assessing the influence of different types of biomass, various configurations of the cooling system, and different biomass heater layouts on thermodynamic, economic, and environmental aspects of the proposed solution. For this, developing a MATLAB code, hourly, monthly, and annual comparisons are made to ascertain the best scenario from different aspects. The economic investigations reveal the superiority of the scenario comprising a specific design of biomass-heater using Prosopis and double-effect chiller with the lowest levelized cost of cooling (LCOC) of 0.031 $/kWh. The integration of a double-effect chiller with this heater using wood chips leads to the lowest emission index of 0.19 kg/kWh. The results further demonstrate that the LCOC is highly sensitive to the fluctuation of the cost of the biomass type, which is a function of availability in different regions of India. Therefore, the study is a secure reference indicating which scenario would result in the best techno-economic-environmental performance among all possibilities in different areas of the country.

The building industry consumes a substantial amount of energy, particularly for heating and cooling, and so contributes significantly to greenhouse gas (GHG) emissions. The vapor absorption chiller (VAC) is one of the most often used cold generating systems for medium and large-scale cooling supplies. Buildings have tended to more commonly use VACs to meet their cooling comfort demands in recent years due to their cost-effectiveness and flexibility of the driving source. Because of the worldwide desire to reduce emissions, the potential of VAC systems with renewable thermal energy systems has made it more appealing. The goal of this analysis is to emphasize the potential integration of VAC with renewable energy technologies including geothermal, biomass, waste heat, surface water, and solar (thermal and PV). This study focuses on the existing and future state of VAC cooling technologies, their technical, economic, and environmental aspects, as well as the framework's analysis and optimization techniques. The paper places a particular emphasis on the cooling-dominated areas of India and Europe. The study finds that, local heat energy availability fosters small-scale circular economies in hot and humid climates, while the high capital costs of transmitting thermal energies across long distances, as well as transmission losses, deter centralized activities. Since there are no HCF emissions, VACs have a major advantage over compression chillers. The findings show that combining VAC with at least four of the six renewable energy sources investigated has enormous potential for the future of clean and sustainable cooling energy alternatives. Small and medium-scale renewable cooling systems, particularly those powered by solar thermal energy, as well as bio-energy, can be cost-effective and installed in a wide range of sites. Solar thermal energy can meet both urban and rural needs, whereas bioenergy is more suited to rural needs. Waste heat recovery systems are mostly utilized to meet industrial cooling needs, and geothermal energy offers a wide range of possible applications but is limited by availability. Bioenergy-based VAC, in particular, has the special advantage of being a carbon-negative solution if the generated bio-char is collected and sequestered.

This work proposes a novel hybrid renewable-based cold production system consisting of an innovative yet simple design of evacuated solar collectors integrated with a biomass heater, thermal storage tanks, and an absorption machine. The optimal design, sizing of the components, and operating conditions of the hybrid system are investigated via thorough techno-economic modeling and dual-objective optimizations for a case study in India. In addition, the assessments cover different designs of biomass heaters and various biomass types. Finally, using the coefficient of performance (COP), the levelized cost of cooling (LCOC), and the emission index as the prioritization parameters, the most efficient, the most cost-effective, and the most environmentally-friendly configurations are indicated. The results show that integrating evacuated plate collectors with a specific design of biomass-heater burning sugarcane baggas is the most appropriate option from all aspects. According to the optimization results, at the best solution point, emission index and LCOC are, respectively, 440.62 kg/MWh and 47.1 USD/MWh. Moreover, the scatter distribution of major decision parameters indicates that while the volume of the hot storage tank is not a sensitive parameter, the chiller temperature and volume of the cold storage tank should be kept at their lowest bounds.

Abstract In the present paper, a vertical ground-coupled heat pump system is proposed for energy saving in a natural gas expansion plant. Such plant is a modern type of conventional natural gas pressure drop station. Unlike the conventional type, which waste the natural gas pressure exergy in throttling process, the modern one uses the pressure exergy of the natural gas for producing electrical power. A remarkable feature of the proposed system is the type of energy resource used for preheating aim. In previous studies, natural gas was used for the preheating process, however; the proposed system employs geothermal energy as a renewable energy resource for providing part of heating demand. Initially, the vertical ground-coupled heat pump system preheats the natural gas stream up to medium temperatures, then, gas stream passes through station heater and reaches the desired temperature. For studying the economic and thermal performance of the proposed system, first of all, a system with a high net present value is selected, and then the performance of the selected system is studied in detail. The analysis revealed that the fuel saving potential of the system is 45.80% annually. Economically, the discounted payback period was also calculated about 6 years.

Large-scale absorption chillers are commonly used for supplying the demand of district cooling networks. In Northern Europe, in many cases, these chillers are driven by local district heating systems which are fed by co-generation waste incineration (WI) plants. Although this configuration performs much efficient during the cold months of the year, it is challenging to manage during the warm months when the operation load in district heating is low. The co-supply of the chillers with WI plant and solar heat is a smart tool to address this challenge provided that one clearly knows which configuration of the hybrid-driven chiller out of the several possible designs results in the best outcomes. This study presents a thorough techno-economic analysis and performance comparison of single-, double- and triple-effect absorption chillers driven by parabolic trough collectors and WI plants for trigeneration of cold, heat and power in a case study in Denmark. The results show that regardless of the absorption chiller type, the use of parabolic trough collectors solves the summer supply problem. Moreover, double- and triple-effect machines lead to a reduction of 45% and 50% in the price of the hybrid system in comparison with the single-effect design. Among the different configurations, the hybrid system integrated with triple-effect design shows the best performance by decreasing the required flow rate of municipal solid waste, and the number of required collectors, and consequently, decreasing the costs.