Annual Average Efficiency Research Articles

Optimization of Optical Efficiency Modeling and Heliostat Field Layout of Tower Solar Thermal Power Station

The aim of this paper is to study and optimize the layout of heliostat mirror fields in solar photovoltaic power plants to improve energy efficiency. By analyzing the key factors of optical efficiency, the optical efficiency model is constructed. The optical efficiency of a single heliostat mirror is calculated using five efficiency factors, namely, shadow shading efficiency, cosine efficiency, atmospheric transmittance, collector truncation efficiency, and mirror reflectivity. The DELSOL layout is used as the initial mirror field, and the mirror field design is optimized by the particle swarm algorithm. The optimal design parameters of the heliostat mirror field including the position of the absorption tower, the size of the heliostat, and the installation height were calculated by adjusting the positions of the heliostat and the absorption tower many times. The results show that the annual average optical efficiency of the heliostat field is 0.6127, and the annual average thermal power output is 37.4508 MW. Through optimization, the annual average optical efficiency of the heliostat field is increased to 0.75, and the annual average thermal power output reaches 64.98 MW. In addition, the results show that the heliostat field has a seasonal characteristic. The optical efficiency and the annual average thermal power output change monthly.

Zero-Energy Purification of Ambient Particulate Matter Using a Novel Double-Skin Façade System Integrated with Porous Materials

This study introduces an innovative double-skin façade system integrated with porous materials (DSF-PM) designed to combat air pollution by purifying atmospheric particulate matter without energy consumption. By evaluating three installation strategies—vertical, horizontal, and cross placement—and examining porous materials with pore sizes of 0.5 mm, 1 mm, and 2 mm through a validated computational fluid dynamics (CFD) model, we optimized the DSF-PM system for enhanced particulate matter purification. Our findings reveal that positioning the porous material on both airflow sides with a pore size of 1 mm yields the best purification performance. The seasonal performance analysis demonstrates that the DSF-PM system achieves an average annual purification efficiency of 26.24% for particles larger than 5 µm, surpassing 20% efficiency, comparable to primary filters in global standards, with zero energy input. This passive double-skin façade system, leveraging solar-driven natural convection, emerges as a sustainable solution for ambient air purification in urban environments.

Energy and exergy analysis of a 20-MW grid-connected PV plant operating under harsh climatic conditions

Abstract Large grid-connected photovoltaic (PV) plants are increasingly being installed around the world, including in harsh desert climates. Evaluating their performance can help improve the design and operation of PV systems. This study performed an energy and exergy analysis of a 20-MW grid-connected PV plant under desert climatic conditions in southern Algeria over a period of 1 year. The PV plant was divided into two 10-MW subsystems. Energy analysis was performed using actual irradiation, power output, wind speed and ambient temperature data. The annual average energy efficiency of the plant and subsystems was 10.82%, 10.95% and 10.69%, respectively. Solar radiation had the most significant impact (80% determination coefficient) on thermal exergy loss. The exergy efficiency of the plant was lower than the literature values, likely due to the harsh desert conditions. The comprehensive energy and exergy analysis provides insights into the performance of large-scale PV plants in desert climates. The results can help guide the system design and operation improvements for such conditions. Regular cleaning and cooling could improve performance.

The Prado Wetlands: 24 years of river diversion treatment wetlands reducing nitrate and phosphate while increasing an endangered bird

Nitrate pollution of surface water from farms and urban runoff is widespread – impairing drinking water supplies, recreation, and wildlife habitat. The scale of the problem in rivers has overwhelmed most watershed-based best management practices. A new paradigm is needed. In this paper we highlight the 119 ha (294 acres) Prado Wetlands in southern California, USA as an example of a gravity-enabled, free surface flow vegetated wetlands to treat a river – the nitrate-rich, effluent-dominated Santa Anna River. The wetland treats ∼1–2 m3/s of the 7.1 m3/s (250 cfs) flow of the river in 28 wetland cells in two parallel trains (residence time 2–4 d, hydraulic loading rate 10–20 cm/d). The cleaner water is returned to the river and infiltrated downstream into a managed groundwater basin supplying 2.4 million customers. Since 1998, ∼1200 t of nitrate-N have been permanently removed from the river and released as N2-gas into the air. Over 24 years, in the warm summers an average of 6.1 mg-N/L entered the wetland and 3.7 mg-N/L flowed out, a removal efficiency of 57%. In the cooler winters, an average of 6.4 mg NO3-N/L entered and 2.6 mg NO3-N/L flowed out, a removal efficiency of 45%. Individual months varied widely in concentration removal efficiency from 7% (winter) to 98% (high summer). Areal summer removal averaged 137 mg NO3-N/m2/d and the apparent “k” was around 46 m/y. All-year rates were 129 mg NO3-N/m2/d or 47 g/m2/y, a reasonable performance considering the size of the system and its configuration for both nitrate removal and duck hunting (i.e., more open water). Annual average nitrate removal efficiency increased substantially over time (45 to 72% for 1998–2004 versus 2016–22) and is attributed to an increase in hydraulic residence time, upgraded internal plumbing, and increased winter temperatures (+3C°). Prado Wetlands also removes phosphorus, though not as well as nitrate; average warm season removal efficiency was 23% (inflow 1.20 mg PO4-P/L, outflow 0.93 mg PO4-P/L). The aerial removal rate was high at 23 mg P/m2/d or 8.5 g/y, probably due to the high inflowing P-concentrations and the hard water. Wildlife was also enhanced. Least Bell's Vireo (Vireo belli pusillus), an endangered bird in the Prado Basin, increased from 19 pairs (1998) to a recent average of 444 pairs due to habitat improvement and reduction of cowbird parasitism. Results from the Prado Wetlands show that cleaning up rivers via diversion through wetlands benefits both water quality and wildlife.

Layout optimization of heliostat field based on genetic algorithm

In order to improve the annual average optical efficiency of a tower solar power plant, a simulated heliostat field layout optimization model is constructed using ray tracing method to calculate the shadow shading efficiency. is constructed using ray tracing method to calculate the shadow shading efficiency. Genetic algorithms are used to encode the variables such as solar pitch angle, solar azimuth angle, and coordinates of heliostat mirrors in chromosomal individuals in binary regions, and to find the near-optimal solutions in iterative populations through the use of ray tracing method. Simulation results show that the model can significantly optimize the layout of the tower solar power system. Simulation results show that the model can significantly optimize the layout of the tower solar power plant and improve the annual average optical efficiency. neighboring heliostats is at 0.398 times the sum of the length and width, the optical efficiency of the Khi Solar One power plant reaches 61.83%, which is an improvement of 15.74% compared to that of the Khi Solar One power plant. improvement of 15.74% compared to this engineering example.

Thermal-Economic Analysis of an Organic Rankine Cycle System with Direct Evaporative Condenser

The organic Rankine cycle (ORC) system for power generation has proven to be an effective technology for low-temperature waste heat utilization. Accurate prediction and comprehensive comparison of system performance under different conditions are necessary for the development and application of suitable ORC configurations. This paper proposed an organic Rankine cycle (ORC) system using a direct evaporative condenser to realize performance enhancement and analyzed its dynamic performance based on the actual climatic condition, which is beneficial for the performance optimization of this system. This study begins with an introduction to the thermal economics model of the proposed system and evaluates the performance of the system based on the 3E (energy, exergy, economy) analysis method. Secondly, four candidate working fluids were compared and analyzed, leading to the selection of R142b as the best working fluid for the proposed system. Finally, the dynamic performance of the proposed system using the working fluid of R142b was analyzed based on the hourly environment temperature. The result showed that the net thermos-electric conversion efficiency of the system was negatively correlated with the ambient wet-bulb temperature. The annual average exergy efficiency of the system is about 65.79%, and the average exergy loss of the heat absorption unit, evaporative condenser, pump, and expander account for 61.07%, 6.92%, 2.99%, and 29.01% of the exergy loss of the system respectively. In the case 8760 h of operation per year, the payback period of the proposed ORC system using direct evaporative condenser is about 2.14 years.

Comparative energy analysis of cooling energy performance between conventional and hybrid air source internet data center cooling system

The widespread need for data processing has led to an increase in internet data centers (IDCs), contributing to the generation of high heat loads and high energy usage. This study discusses a simulation model of a newly proposed cooling system applied to data centers for five selected climatic areas in South Korea. Using experimental data of the newly proposed system, performance correlations are developed by regression analysis method to estimate performance curve coefficients for energy modelling and simulation to predict the annual energy performance of the system and compare the performance with that of a conventional cooling system. The results showed an overall annual average energy efficiency of approximately 14.1% of the hybrid cooling system over the conventional cooling system. The mean seasonal coefficient of performance (SCOP) for the hybrid system and the conventional system is approximately 6.7 and 4.9 respectively for all cases in the winter period while a SCOP of 3.2 and 3.7 respectively for the summer period.

Assessment of ternary CO2 mixtures as working fluids in supercritical Brayton cycles with floating critical points

The performance of the supercritical CO2 (sCO2) Brayton cycle deteriorates due to the mismatch between critical temperature and cold source temperature. An innovative solution based on ternary CO2 mixtures with adjustable compositions is proposed to expand the variation range of the critical temperature. An in-house MATLAB code is developed to investigate the design-point performance of the proposed system. The results indicate that the effect of improving cycle efficiency by using the modified floating critical point method becomes increasingly significant as the target critical temperature deviates from that of CO2. The CO2–H2S–Kr is screened out as the best ternary mixture, with the cycle efficiency being increased by over 8 % compared to the sCO2 cycle at very high (45 °C) and low (−15 °C) temperatures. The long-term performance is also evaluated based on the hourly historical weather data of two typical climate regions. The annual performance depends on both the average value and the distribution characteristics of the local ambient temperature. A relative improvement in annual average efficiency of 7%–9.56 % can be obtained depending on the regions. The present work is helpful to make the supercritical Brayton cycle give full play to its efficiency advantage in a wide cold source temperature range.

Potential of applying the thermochemical recuperation in combined cooling, heating and power generation: Optimized recuperation regulation with syngas storage

In the traditional combined cooling, heating, and power (CCHP) systems, the frequently changed user loads result in unfavorable supply-demand matching characteristics, which weakens the practical operational regulation performance. In this work, the thermochemical recuperation (TCR) with syngas storage method is proposed to optimize the system regulation characteristics and enhance the waste heat recovery. Various building energy load scenarios are also adopted to comprehensively evaluate the modified CCHP system operation characterizes. Meanwhile, with the consideration of reasonable operation regulation of syngas storage and multi-energy demands supplementary between different buildings, the coordinated system energy scheduling capacity are deeply explored to investigate the practical system application feasibility. The results indicate that under the designated operating conditions, the cooling/heating-to-power output ratios have been adjusted from 2.45 and 2.73 to 0.24–2.55 and 0.64–2.85, respectively. Additionally, with the efficient operation regulation process of TCR and syngas storage, the annual average energy utilization efficiency of the hotel, hospital, office and shopping center will be increased by 3.88%, 3.85%, 4.50% and 3.98%. Besides, through the synergistic complementary of syngas storage and adjustment between shopping center and hospital, the annual average syngas storage utilization rate of the shopping center can be increased from 16.99% to 97.41%, with the annual fuel consumption reduction of 5.78% in hospital scenario. This paper provides a combined TCR and syngas storage regulation method for the CCHP system, which enhances the system energy output flexibility and waste heat recovery capabilities in the distributed energy system application.

Determining the efficiency of installing fixed solar photovoltaic modules and modules with different tracking options

The object of this study is photovoltaic modules in various installation options. The physical model of the Earth's illumination by a parallel flow of solar rays has been refined. The dependence of the cosine of the angle of incidence of the Sun's rays on the angular length of the day, as well as the average annual efficiency of the installation of photovoltaic modules, both fixed and with various tracking options, was determined. Refinement of the physical model implies determining the angle of inclination as the angle between the inclined axis of the Earth and its projection on a vertical plane, perpendicular to the line connecting the centers of the Earth and the Sun. This line passes through the center of the Earth. The concept of the average annual efficiency of the installation of photovoltaic modules is introduced as the annual weighted average value of the cosine of the angle of incidence of solar rays on the plane of the photovoltaic module. Various options for installing photovoltaic modules were analyzed: fixed horizontal on the equator; stationary, installed at an angle to the horizon; one that performs tracking in horizontal (vertical) planes; with full tracking. The efficiency of installing a photovoltaic module at each latitude can be equal to the efficiency of installing this module at the equator, that is, 47.93 % when installing the module at an angle of inclination to the horizon equal to the latitude. Tracking in the vertical plane makes it possible to increase the efficiency of the photovoltaic module installation by up to 50 %. Compared to full tracking, tracking in the horizontal plane at an angle of latitude makes it possible to obtain the efficiency of the installation of the photovoltaic module at the level of 97.93 %. The results could be used as a basis for evaluating the efficiency of the installation of photovoltaic modules at different latitudes with different techniques of their installation, as well as for the subsequent generation of electricity

Performance analyses and optimization studies of desiccant wheel assisted atmospheric water harvesting system under global ambient conditions

A heat pump driven atmospheric water harvesting system, which can be operated under direct cooling mode and desiccant wheels assisted cooling mode, was proposed in this paper. Investigations were carried out to find out the optimal operation mode and operation parameters under different ambient conditions and daily water harvesting requirements. Optimization studies were firstly carried out on each operation mode to find the recommended operation parameters, namely evaporation temperature and daily operation hours, for different ambient conditions, daily water harvesting rate and maximum operating hours. Then, the optimal operation modes, which has lower daily power consumption under their own recommended operation parameters, were suggested on the psychrometric chart. The results showed that, for different combinations of daily water harvesting rate and maximum operating hours, there exist a critical humidity ratio and a critical relative humidity ratio for each case. When ambient air relative humidity and humidity are both higher than the critical values, it is recommended to use the direct cooling mode. Otherwise, the desiccant wheels assisted cooling mode should be used. Lastly, performances of the system in different climate zones were analyzed. Under the optimal operation mode, the annual average water harvesting efficiency was from 1.08 to 1.22 kg/kWh in Urumqi, from 1.50 to 1.78 kg/kWh in Beijing, and from 2.22 to 3.72 kg/kWh in Haikou, respectively, when daily water harvesting rate is from 50 to 200 kg/day and maximum operating hours is from 6 to 10 h.

Co-simulation-based conventional exergy evaluation of a hybrid energy generation-vanadium redox flow battery-air source heat pump system

A conventional exergy assessment approach permits determining the magnitudes of irreversibility that have happened within the investigated system components, which indicates the potential for improvement for these components. In this study, this approach was applied to a hybrid powered air source heat pump with vanadium redox flow battery system through co-simulated (solar photovoltaic and wind turbine) TRNSYS integrated with MATLAB Simulink) work. Due to the absence of a sophisticated VRFB model in the TRNSYS application, the battery model created in the Matlab Simulink environment was utilized and then summoned into the TRNSYS simulation studio by use of the TRNSYS utility model.Exergy destruction and exergy efficiency were used as performance criteria for evaluating the conventional exergy performance of the utilized components in the established co-simulation model. While yearly cumulative exergy destruction values ranged from 194.2 kWh for R to 23318.2 kWh for the PV field, annual average exergy efficiency amounts varied between 0.0494 for ASHP and 0.9345 for R. The PV field with the highest exergy destruction and relatively low exergy efficiency causing the highest improvement priority, but the opposite is true for power conditioning equipment, specifically IR and R.

Compressed air and hydrogen energy storage hybridized with solar energy to supply electricity and hot water for a residential settlement

In order to move toward net zero energy buildings, use of new and renewable energy resources parallel with development of high performance energy storage systems is necessary to maximize energy absorption and reduce energy losses with subsequent improvement in the energy performance of systems. In this research, two separate energy storage systems for supplying electricity and hot water for 500 residential buildings in Beijing have been designed and compared based on their performance. 1500 solar panels provide the required power for buildings. The first system is compressed air energy storage (CAES), while the second system is hydrogen energy storage (HES). Simulation has been done in TRNSYS and EES software. Energy and exergy analyses have been done for both systems. In case of the loss of hot water produced by the systems, the annual average energy efficiency of CAES and HES is about 44 % and 42 %, respectively. The energy efficiency of the first system decreases in the hot months of the year and reaches about 42 %, but the efficiency of the HES system is constant throughout the year. If the hot water produced by the systems is used for consumption in residential buildings, the energy efficiency of CAES and HES reaches 93 % and 64 %, respectively. The most exergy destruction in the CAES is related to combustion chambers (41 % of the total exergy destruction) and in the HES, it is related to electrolyzers (71 % of the total exergy destruction). The exergy efficiency of the first system is about 56 %, while for the second system this value is about 34 %.

Coupling a road solar thermal collector and borehole thermal energy storage for building heating: First experimental and numerical results

The adoption of more efficient technologies that integrate renewable resources for heating buildings is a key action for increasing sustainability in the residential sector in the European Union. Borehole thermal energy storage and road thermal collector systems, which have mainly been integrated in colder countries to develop renewable systems, aimed at preventing the freezing of road surfaces in winter, could also be used in warmer countries to develop sustainable heating systems for buildings. In this experimental–numerical study, the possibility of integrating these two systems for the heating of buildings located in the Mediterranean region is investigated for the first time. To this end, a pilot plant was built at the facility test site of the University of Palermo, with the aim of demonstrating the possibility of storing solar energy in summer and recovering it in winter. A new method is proposed to characterize both the thermal conductivity and diffusivity of the different materials in the design phase of the plant. The results of simulations conducted with a validated numerical model show that the proposed system, characterized by an average annual collector efficiency of 10% and a seasonal storage efficiency of 80%, can reduce the length of borehole heat exchangers by about three times compared with a conventional geothermal heat pump plant.

Healthcare Service Efficiency: An Empirical Study on Healthcare Capacity in Various Counties and Cities in Taiwan.

As human lifespan increases and the need for elderly care grows, the demand for healthcare services and its associated costs have surged, causing a decline in the operational efficiency of universal healthcare. This has created an imbalance in medical services across different regions, posing a long-standing challenge for the public. To address this issue, strategies to enhance the capacity, efficiency, and quality of healthcare services in various regions must be developed. The appropriate allocation of medical resources is a fundamental requirement for countries to establish a robust healthcare system. This empirical study utilized data envelopment analysis (DEA) to evaluate the efficiency of medical service capacity and identify potential improvement strategies for counties and cities in Taiwan during the period from 2015 to 2020. The results of this study show that (1) the annual average efficiency of medical service capacity in Taiwan is approximately 90%, indicating that there is still room for a 10% improvement; (2) among the six municipalities, only Taipei City has sufficient healthcare capacity, whereas the efficiency of the remaining municipalities needs improvement; and (3) most counties and cities demonstrated increasing returns to scale, indicating a need to scale up the capacity of medical services as appropriate. Based on the findings of this study, it is recommended that medical personnel be increased accordingly to balance the workload, a favorable working environment be provided to stabilize the medical workforce, and urban-rural medical disparities be balanced to improve service quality and reduce cross-regional health services. These recommendations are expected to provide a reference for society as a whole to promote and enhance public health policies, leading to a continual improvement of the quality of medical services.

Renewable energy generation efficiency of Japan’s administrative regions: An application of the dynamic slacks-based measure

This paper demonstrates how to compute the regional renewable energy generation (REG) efficiency by output-oriented dynamic slacks-based measure (DSBM) model proposed by Tone and Tsutsui (2010). The research objects are 47 administrative regions in Japan during 2016–2019. The annual average REG efficiency (REGE) scores of all regions and areas in Japan were below 30 %, implying a 70 % room for increasing the REG output. The southwest regions in Japan are mainly rural and have low population density, whereas their REGE is relatively higher than others’. Conversely, the REGE of the regions with high population density in the Pacific Belt Zone is relatively lower. The REGE in Japan has slightly improved over the data period. The random-effects panel-data Tobit regression shows that the REGE is negatively related to population density and increases with regional income. A highly populated region such as Tokyo can still be REG-efficient by fully utilizing its installed capacity and potentials. The green finance hence is important to facilitate the RE development in low-income regions.

Design procedure of stationary compound parabolic concentrator with flat plate absorber for effective year-round performance – Response Surface Methodology and Tracepro as tools

The stationary Compound Parabolic Concentrators (CPC) with a low concentration ratio (C<2) are suitable for pre-heating processes in industrial applications. The reported literature does not analyze the radiation available or the solar angles for whole year towards design of CPC which could provide maximum annual energy. This paper optimizes the design factors of CPC, such as acceptance half-angle (θa) and truncation ratio (TR), to yield maximum energy around the year, maximize optical efficiency and minimize reflector material. Annual irradiation data for the location - Tiruchirappalli, Tamilnadu, India (ϕ- 10°45′36″ N) is considered for the present study. The raw irradiation data is processed to get monthly average daily data, which is used as input for the TracePro v21.1. The experimental design (DOE) is made in response surface methodology (RSM) by considering the factors of θa - 18.5 to 28.5° and TR - 0.5 to 1.0. Nine Geometric models were created using Solidworks based on the combination of parameters given by RSM and simulated using TracePro to estimate the annual energy collection and average optical efficiency. Using the TracePro analysis month wise energy collection is calculated and reported. Further, a model relating θa and TR to the annual energy collected was obtained. According to the results obtained from the multi-objective optimization, the optimum concentration ratio is 2 with the θa of 28.5° without truncation. The results also indicate that the deviation from the average energy collected by the optimized design over the year is less when compared to the other designs.

Modelling PM10 removal in three Italian coastal Metropolitan Cities along a latitudinal gradient

Air pollution is regarded as the largest environmental risk factor in Europe, and Particulate Matter (PM) is considered one of the most harmful pollutants. Among the Ecosystem Services (ESs) it provides, the Urban Green Infrastructure (UGI) is capable of capturing and adsorbing pollutants through removal mechanisms. As envisaged in the National Plan for Recovery and Resilience (PNRR), Italy has planned on investing about EUR 300 million of the Next Generation EU funds in urban reforestation programs that will target Italian Metropolitan Cities (MCs). Successful implementation of such interventions is underpinned by a thorough knowledge of the presence and distribution of existing vegetation and its capacity to deliver ESs. In the present study, we selected three Italian coastal MCs along a latitudinal gradient, namely Genoa, Bari, and Reggio Calabria, and assessed the regulating ES of PM10 removal by urban and peri-urban forests in both biophysical and monetary terms. In 2019, the total PM10 removal in the MCs of Genoa, Bari and Reggio Calabria amounted to 5,331, 363, and 4,248 Mg respectively, for a corresponding monetary value of EUR 536, 39, and 435 million. Our analyses were conducted on a seasonal basis and further aimed at investigating the role of functional diversity in ES provision. According to our findings, in all MCs the highest annual average PM10 removal efficiencies were exhibited by the evergreen broadleaves; deciduous broadleaves also displayed high efficiency values, despite being characterized by a marked seasonality caused by leaf abscission. Conifers proved less efficient, although our findings may indicate a good response to a condition of multi-stress. Maintaining a functionally-mixed species composition in the UGIs is desirable for guaranteeing the continuous provision of ESs throughout the year. In conclusion, our results provide useful insights to support the sustainable planning and management of UGIs, as envisaged by the United Nation's 2030 Agenda for Sustainable Development.

Assessing the influence of time-dependent power grid efficiency indicators on primary energy savings and economic incentives for high-efficiency cogeneration

In Italy, the economic support scheme for high-efficiency cogeneration annually provides tradable White Certificates to new constructed or refurbished high-efficiency cogeneration plants over a period of 10 years, proportionally to their annual primary energy saving. In contrast to the legislation currently in force, which assumes the power grid efficiency constant, this paper aims at assessing the adoption of a time-dependent approach, based on the use of the thermoelectric-based power grid efficiency, for evaluating the primary energy saving ensured by high-efficiency cogeneration as well as the relating economic incentives. The case study being analysed includes two 5.5 kWel micro-cogenerators installed in Naples (South Italy). Beyond the conventional, three scenarios have been outlined, depending on the time accuracy adopted (yearly, monthly and hourly basis). Starting from 2016, the scenarios have been replicated over the ten-year incentive period. In particular, the annual average thermoelectric-based power grid efficiency has been forecasted from 2021 to 2025. Following the innovative approach proposed in this study, the White Certificates would have increased by 9.2% in 2016, by 6.1% in 2017 and by 6.1% in 2018 too, thus fostering the achievement of the targets about high-efficiency cogeneration at national level.

Optical and thermal performance analysis of a compact solar collector with heat-pipe evacuated tube

Process industry consumed 15 % to 30 % of the global energy, and 40 % of it is thermal energy demand in the range of 80 °C-250 °C. To produce mid-temperature heat, a new solar collector was designed with heat pipe evacuated tube, including several parallel micro-parabolic troughs, heat pipes, double-layer vacuum tubes contained in a compact frame and an external mechanical solar tracker. In addition, the selective absorbing coating (SAC) was applied on the inner surface of the vacuum tube, and the gap between the heat pipe and the vacuum tube was filled with heat transfer oil. Since the height of the designed collector was only 124.5 mm, it can be easily integrated with buildings. Genetic algorithm (GA) was used to optimize the structural parameters based on maximum obtained solar energy of the collector, and theoretical analysis and numerical simulation are carried out for optical and thermal performance of the collector. The analytical and numerical results showed that the annual average optical efficiency is 57.6 % and the thermal efficiency is 30.6 % at 250 °C when the normalized temperature difference is 0.23. By exergy analysis, the collector has a maximum exergy efficiency of 15.5 % with operating temperature of 204.4 °C, which is the station of the best thermal performance of the collector. Furthermore, theoretical model was verified to be valid by a prototype. Overall, the proposed collector is suitable for mid temperature industrial applications and integrated with rooftop.