• Energy Research
• 2021-2025close

The present work introduces an innovative yet feasible heating system consisting of a ground source heat pump, borehole thermal energy storage, an auxiliary heater, radiators, and ventilation coils. The concept is developed by designing a new piping configuration monitored by a smart control system to reduce the return flow temperature and increase the temperature differential between the supply and return flows. The radiators and ventilation heating circuits are connected in series to provide the heat loads with the same demand. The investigation of the proposed model is performed through developed Python code considering a case study hospital located in Norway. The article presents, after validation of the primary heating system installed in the hospital, a parametric investigation to evaluate the effect of main operational parameters on the performance metrics of both the heat pump and the total system. According to the results, the evaporator temperature is a significant parameter that considerably impacts the system performance. The parametric study findings show that the heat pumps with a thermal capacity of 400 kW and 600 kW lead to the highest heat pump and total seasonal performance factors, respectively. It is also observed that increasing the heat pump capacity does not affect the performance indicators when the condensation temperature is 40 °C and the heat recovery is 50%. Moreover, choosing a heat pump with a smaller capacity at the heat recovery of 75% (or higher) would be an appropriate option because the seasonal performance values are not varied by changing the heat pump capacity. The results reveal that reducing return temperature under a proper parameters selection results in substantially higher seasonal performance factors of the heat pump and total system. These outcomes are in-line with the United Nations sustainable development goals including Sustainable Cities and Communities.

This study introduced an innovative yet feasible and cost-effective solution to make a big step forward in the state-of-art of smart energy buildings and obtain a real meaning of net-zero energy building. In this study, the main cornerstones of the developed solution combined the following technologies: the use of novel trigeneration solar collectors without a battery, a very clever method of heat pump integration with minimal size and cost required, and two-way interaction of the building with local energy networks. Different system configurations based on the included components were suggested and analyzed for an apartment building in Denmark. A thorough techno-economic and environmental evaluation of the proposed solution and the most competent ones already proposed for the same application was carried out to rank the best configuration from various facets. A comparative parametric study was accomplished to examine and compare the variation of performance indicators with significant decision variables. In addition, the tri-objective optimization was implemented for each configuration to specify the best optimum condition from energy, economic, and environmental standpoints. According to the economic results, the configurations integrated with battery and regular heat pumps were not favorable due to the highest total cost and the payback period. Here, the proposed system, owing to its resilient energy trade possibility with the energy networks and the scaled-down heat pump, gave larger energy-saving and CO2 emission reduction rates of 16.6% and 21.6%, respectively. The multi-objective optimization showed that the capacities of the battery and the cold storage were the most effective parameters on the performance of the system.

In the present study, innovative energy efficiency enhancement methods and cleaner production in conventional waste-fired CHP plants are presented. This includes the medium- and low-grade solar thermal systems and flue gas condensation for feedwater heating in different arrangements. The article presents a thorough thermodynamic, economic, and environmental assessment of all the possible scenarios and then ranks the best solutions in different aspects. For making the results reliable, the solutions are applied to a waste-fired CHP plant in Denmark. For this, a transient simulation of the proposed configurations is performed via TRNSYS software for an entire year. The results indicate that the proposed models can produce more power and heat than the conventional plant but with different effectiveness factors. According to the economic results, a design consisting of a flue gas condensation circuit and parabolic trough collectors for the open and closed feedwater heater form the best configuration. The exergy assessment results indicate that the waste incinerator with annual irreversibility of 128.4 GWh is the most important component exergetically. Finally, the parametric study results show that the increase of incineration temperature significantly affects the power and heat exergy efficiency ratios.

In the present work, a novel hybrid solar-based smart building energy system is introduced and studied. The system comprises innovative photovoltaic-thermal-cooling (PVTC) panels integrated with hot and cold storages with two-way interaction with electricity, heat, and cooling networks (if any). The proposed system is compared with PV-based systems integrated with battery and heat pump for a case study complex building in Aarhus, Denmark. The comparison is conducted by evaluating the performance and economic indicators and investigating the effect of significant parameters on each scenario via a parametric study. Furthermore, the optimal operating conditions and sizing of the proposed system are determined using the genetic algorithm method considering initial cost and traded energy with local energy networks as the objective functions. The comparison results show that the proposed solution is the most cost-effective scenario with the lowest initial cost of about 457,000 $ and a payback period of 6.6 years. This is mainly due to the simultaneous interaction with electricity/heat/cooling networks as well as the elimination of the battery and the heat pump, which are offered by the proposed scenario. It is shown that, in comparison to PV panels, the PVTC can produce 328.7 MWh and 125.6 MWh extra heat and cooling annually. The scatter distribution of significant parameters shows that the panel area and heat storage capacity are not sensitive parameters, and keeping the cold storage capacity at the lower bound is a techno-economically better option.

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.