Concentrated Solar Power Systems Research Articles

Enhanced high-temperature thermal stability of the novel MoAlSiN-based solar selective absorbing coatings by optimizing the multilayer structure

Solar selective absorbing coating (SSAC) plays an important role in the high-temperature concentrated solar power system. The high thermal stability of SSAC above 600 °C has been a big open question for molten salt concentrated solar power projects. In our work, the TiN/Mo/MoAlSiN/MoAlSiON/SiO2 and the TiN/Mo/MoAlSiN/Si3N4/SiO2 SSACs are developed for getting high-temperature thermal stability, besides excellent spectral selectivity. The solar spectral absorptivities of the MoAlSiN/MoAlSiON and MoAlSiN/Si3N4 SSACs are 95.2% and 93.2%, respectively. While the infrared emissivities of the MoAlSiN/MoAlSiON and MoAlSiN/Si3N4 SSACs are controlled below 10.6% and 10.5% at 400 °C, respectively. The novel MoAlSiN/Si3N4 SSAC deposited on quartz can maintain thermal stability even after heat treatment at 800 °C for 200 h in vacuum, which is one of the best results in the research field for high-temperature SSACs. It is found that the choice of suitable materials without oxygen and the elimination of interfacial thermal stress are very important for improving thermal stability. Furthermore, the practical total energy conversion efficiencies of the MoAlSiN/Si3N4 SSAC at 600 °C–800 °C are always above 57%. When the activation energy is assumed as 180 kJ/mol, the estimated service life of the MoAlSiN/Si3N4 SSAC at 600 °C is more than 25 years.

Techno-economic assessment of a numbering-up approach for a 100 MWe third generation sodium-salt CSP system

This work presents the design and techno-economic analysis of a 100 MWe concentrated solar power (CSP) system using a supercritical CO2 power block with 700 °C input temperature. Aiming to leverage the relatively higher efficiency of small heliostat fields and potential multi-build discounts, a numbering-up approach is examined, developing four alternative configurations (1×100, 2×50, 3×33, and 4×25MW˙e), in which each module has its own dedicated tower, heliostat field, receiver, thermal storage and power block. A comprehensive techno-economic model is combined with detailed annual simulations to yield levelised cost of energy (LCOE) estimations and analyse the potential of system numbering-up for high-temperature next-generation CSP systems based on liquid heat transfer fluids (HTFs). The simulations are verified against the System Advisor Model with differences in the LCOE calculations within ±1.0%. Comparing the four systems shows that a 1×100MW˙e system leads to an LCOE of 54.88USD/MWh˙e, lower than for the numbered-up modules. However, the LCOE difference between configurations with one and two modules is moderate, with the 2×50MW˙e configuration showing an LCOE of 55.99USD/MWh˙e (+2%). Despite their higher annual conversion efficiencies, the 3×33MW˙e and 4×25MW˙e systems are more capital-intensive and escalate LCOE by 6.9 and 12.2%, respectively. With size-dependent power block efficiency, further LCOE escalation with numbered-up systems is observed, however, multi-build savings could potentially reverse this cost escalation and a 13.9–19.6% saving on the two-module system would allow them to break even.

Strength analysis of molten salt tanks for concentrating solar power plants

Promoting the development of concentrating solar power (CSP) is critical to achieve carbon peaking and carbon neutrality. Molten salt tanks are important thermal energy storage components in CSP systems. In this study, the cold and hot tanks of a 100 MW CSP plant in China were used as modeling prototypes. The materials and geometric models were determined based on related specifications and engineering experience. Mechanical characteristics of the tanks under steady condition, including the deformation, stress distribution, and stress concentration, were simulated and calculated. Furthermore, the strength of the tank walls was evaluated. The findings can be used as a reference for designing the molten salt storage tank and reducing the risk during the operation.

Temporal performance indicators for an integrated pilot-scale membrane distillation-concentrated solar power/photovoltaic system

Management of concentrate streams in inland applications has uncertain long-term environmental impacts. This study investigates an intensified solar-energy capture desalination system that integrates membrane distillation (MD) with a hybrid concentrated solar power (CSP)/photovoltaic (PV) collector to realize self-sustained zero-waste discharge for effective management of concentrate streams in inland and off-grid applications. The demonstration-scale CSP/PV system can produce up to 178 kWh of thermal energy and 4 kWh of electrical energy per day. The thermal and electrical energy from the CSP/PV system is directly supplied to the air gap MD (AGMD) pilot-scale system producing up to 288 L of distilled water per day. Experiments were performed on the hybrid AGMD-CSP/PV system to evaluate system performance under various operating conditions including AGMD and CSP flow rates, CSP system pre-heating, and AGMD vacuum pressure. Experimental results indicate that doubling the AGMD flow rate results in a 119% increase in thermal energy utilization and a 71% increase in distillate production. Compared to the winter months, operating the system in summer months when direct normal irradiance (DNI) is highest results in nearly double the distillate production (88 L in winter and 168 L in summer) and nearly three times the amount of thermal energy consumption (15 kWh in winter and 43 kWh in summer). Operating with vacuum resulted in a 34% increase in distillate production and allowing the thermal storage reservoir to preheat in the winter resulted in a 61% increase in distillate production. Overall, experimental results highlight the tradeoff between distillate production and thermal and electrical energy production and consumption under various environmental conditions and the potential for AGMD-CSP/PV to be a stand-alone desalination system.

Geographical information systems based site selection methodology for renewable energy systems in Palestinian territories

<span lang="EN-US">Renewable energy is the key term for the energy industry sector in the world recently. Palestinian territories (PT) have good potential for multiple renewable energy applications. The purpose of this study was to evaluate the potential sites for solar photovoltaic systems, concentrated solar power systems, and wind farms in the West Bank (WB). The study was derived from geographical information systems (GIS) and multi-criteria decision making (MCDM). The criteria for each application were identified and weighted according to the analytical hierarchy process (AHP). All the resulting layers were multiplied to produce the final suitability map for each application. The results of the study depend on two scenarios, In the first scenario, where area C is included, the areas classified as highly suitable for photovoltaic (PV), concentrated solar power (CSP), and wind turbines are between 14.27 and 7.56 km<sup>2</sup>. The second scenario is excluding area C, the highly suitable areas were between 4.1 to 2.47km<sup>2</sup>.</span>

Evaluation of the calcium chloride-calcium fluoride system for high temperature thermal energy storage

The storage of excess or unutilised energy generated by renewables remains a key unsolved piece in the decarbonisation of the energy sector. One potential way to solve this is through the use of thermal energy storage which can use the heat as is (e.g., in concentrated solar power systems) or through the conversion of electricity to heat (e.g., through resistive heating) at very low costs. To achieve these low costs, high storage densities and low-cost materials should be utilised. A potential way to achieve this is by harnessing the energy released during phase change in appropriate materials such as molten salts. Therefore, the current study investigates calcium chloride and mixtures of calcium chloride and calcium fluoride as storage options. Aside from the pure salt, a eutectic was found at 647 ± 1.7 °C and 18.3 mol% calcium fluoride, while a peritectic was also found at 730 ± 2.3 °C and 41 mol% calcium fluoride. Determination of the storage density of the materials was undertaken using differential thermal analysis and differential scanning calorimetry to measure the enthalpy of transition and specific heat capacity. These results showed high heats of transition (298–310 ± 15.0 J/g) and heat capacities (0.72–1.02 ± 0.1 J/g∙K) making them potentially a cost-effective high temperature storage medium.

Modeling of a hybrid power system integrating solar radiation and syngas combustion energy

AbstractThis study aims to model a hybrid power system that can continuously generate power by switching between two possible thermal sources: solar radiation and combustion energy from synthesis gases. The system comprised a hybrid energy receiver, solar dish, Stirling generator, fluidized‐bed gasifier, boiler, and water tank. The solar dish was a dual‐reflection solar collector that used two mirrors, namely the main and subordinate concentrators, to concentrate a broad expanse of solar radiation onto a hybrid energy receiver. The fluidized‐bed gasifier was employed for the production of synthesis gases. The synthesis gases were combusted to provide an auxiliary heat source for the Stirling generator when solar radiation was insufficient. Solar radiation or combustion energy was alternatively introduced into the hybrid energy receiver and converted to power by a 1‐kW‐scale beta‐type Stirling engine. In this manner, the Stirling generator could serve as a base‐load power plant regardless of solar conditions. In this study, a complete quantitative model was developed for a demonstration plant by incorporating thermodynamic and dynamic models of the beta‐type Stirling engine, a ray‐tracing model for the dual‐reflection solar dish, an energy model of the hybrid energy receiver, and experimental data for the fluidized‐bed gasifier. The performance response of the system during switching between solar radiation and combustion energy was predicted. The modeling results indicated that switching can result in a continuous power output ranging from 600 to 1200 W. With synthesis gas combustion as the auxiliary heat source, the hybrid Stirling power system can be operated continuously, and the overall power output is increased by 109.82% compared to a conventional concentrated solar power system that only uses solar radiation.

Techno-economic optimization of molten salt based CSP plants through integration of supercritical CO2 cycles and hybridization with PV and electric heaters

The present study explores the integration of supercritical CO2 (sCO2) power cycles into Concentrating Solar Power (CSP) plants using molten salt, and the hybridization of these plants with solar photovoltaic (PV) systems through electric heaters. Techno-economic evaluations determined the optimal power cycle configuration and subsystem designs for two different scales and locations and then compared them with state-of-the-art solar power plants. The results show that hybridizing PV with state-of-the-art CSP can lead up to a 22% reduction in the Levelized Cost of Electricity (LCOE) compared to standalone CSP systems. This hybridization and the use of electric heaters are particularly beneficial for small-scale installations and locations with low DNI/GHI ratios. By replacing the steam Rankine cycle with a sCO2 power block, a further 42% reduction in LCOE can be achieved at small scales, even with a simple recuperated cycle. In conclusion, the hybridization with PV and the integration of sCO2 power blocks provide cost benefits despite the temperature limitations imposed by the molten salt. Hybrid PV-CSP plants with sCO2 power blocks prove to be a cost-effective solution for capacity factors exceeding 60%. For lower capacity factors, configurations combining PV with battery energy storage or PV with electric heaters, thermal energy storage, and sCO2 power blocks are preferable options.

Pengembangan Alat Desalinasi Air Laut dengan Teknologi Thermal Energy Storage

The need for clean water in household life is very important because humans cannot live without it. The composition of seawater consists of 96.5% pure water and 3.5% other materials, namely salts, dissolved gases, and others. Indonesia is one of the countries that has the second-longest coastline in the world, so the potential for utilizing sea water is very large, one of which can be through the desalination process. Distillation itself is distillation, and its by-product is salt when seawater is heated using a heat energy source with a concentrated solar power (CSP) system. Based on research that has been done previously, the tool is a lab-scale seawater desalination device, but the process of making a lab-scale seawater desalination tool is not optimal. Then design the construction of a lab-scale seawater desalination device with the Multi Stage Flash (MSF) type, and the aim is to determine the performance and functionality of the MSF-type lab-scale seawater desalination device. The results show that the results of the coil heat exchanger development obtained an inlet temperature of 85.9°C and an outlet temperature of 67.8°C, and the room temperature in the chamber can be maintained at a temperature of 68.9°C. As for the components being developed, such as sea water pumps, hoses, tees, and sprayers, a sea water debit of 53.78 liters per hour has been obtained.

A transient study on a solar-assisted combined gas power cycle for sustainable multi-generation in hot and cold climates: Case studies of Dubai and Toronto

Efficiently managing heat losses continues to be a prominent obstacle within gas-fired power plants. The discharge of high-temperature gases from turbines and the considerable pressure generated by compressors present compelling opportunities for augmenting both power generation and overall efficiency. The present study analyzes a gas-fired power plant with two additional Rankine cycles and a concentrated solar power system to enhance efficiency and output power. Clean power generation and distilled water were the outputs of the proposed system. This study also sought to reduce greenhouse gas (GHG) emissions by using solar energy and diminishing the consumption of fossil fuels (CH4) in the combustion chamber. The proposed system was implemented in hot and cold climates. The Brayton cycle of the system was validated through data of a real-life power cycle on the southern coasts of Iran. Furthermore, a transient evaluation was conducted to explore the effects of climatic parameters on the power and desalination system. The contributions of solar irradiance, wind speed, and ambient temperature to the proposed system in a hot climate (Dubai, UAE) and a cold climate (Toronto, Canada) were evaluated. It was found that gas turbine efficiency, compression ratio, and gas turbine input temperature had the greatest effects on the system. Exergy analysis revealed that the combustion chamber, heliostats, the solar receiver, the multi-effect distillation (MED) unit, gas turbine 1, and the thermoelectric generator accounted for the largest portion of the exergy destruction. The case study indicated that the system would work best in climates like Toronto. The findings can be useful to investors and governments in such climates. The proposed system demonstrates its adaptability to regions sharing a climate resembling that of Toronto, making it a viable solution for a wide range of geographical areas. The design and functionality of the system have been meticulously crafted to accommodate the specific environmental conditions present in Toronto and its comparable regions. Gas-fired power plants across numerous countries widely employ the Brayton cycle as their primary operational framework. In this context, the proposed system presents a compelling opportunity to unlock valuable outcomes and advancements.

Integration of calcium looping and calcium hydroxide thermochemical systems for energy storage and power production in concentrating solar power plants

Energy storage is a key factor in the development of renewables-based electrical power systems. In recent years, the thermochemical energy storage system based on calcium-looping has emerged as an alternative to molten salts for energy storage in high-temperature concentrated solar power plants. This technology still presents some challenges that could be solved by integrating the thermochemical energy storage system based on calcium hydroxide. This work studies a novel concentrated solar power system integrating calcium-looping and calcium hydroxide thermochemical energy storage systems. The results show that the combined use of hydration-dehydration cycles in the calcination-carbonation processes of the calcium looping for energy storage could partially solve the issue related to the multicyclic deactivation of calcium oxide. The improvement in the conversion of calcium oxide during carbonation is demonstrated experimentally when hydration-dehydration cycles are combined. Numerical simulations demonstrate the technical feasibility of the integrated process, with efficiencies ranging between 38-46%, improved with the increase in calcium oxide conversion in the carbonator, showing the potential of the proposed integration.

Operation Performance Analysis of a Novel Renewable Energy‐Driven Multienergy Supply System Based on Wind, Photovoltaic, Concentrating Solar Power, Proton Exchange Membrane Electrolyzers, and Proton Exchange Membrane Fuel Cell

In pursuing clean energy systems and carbon neutrality, the efficient use of renewable energy is key. This research introduces a novel wind–solar–hydrogen multienergy supply (WSH‐MES) system, powered by renewables, designed to stabilize power output through regulated concentrating solar power (CSP) and proton exchange membrane electrolyzers (PEMEs). An active regulation strategy for thermal and hydrogen storage is developed to counterbalance the volatility of wind and photovoltaic power. Key results reveal that the WSH‐MES system surpasses WP–PV and WP–PV–CSP systems in reliability, reducing power supply loss probability to 2.81%. This improvement is largely due to the controlled CSP and PEME, which effectively mitigates the stochastic fluctuations in wind and solar power generation, thereby ensuring more stable and reliable power output. Moreover, the system achieves an 80.97% primary renewable energy rate and a 0.12 power discard rate. In conclusion, this research comprehensively examines the operational characteristics of the WSH‐MES system, elucidates the practical advantages of the WSH‐MES system in terms of reliability, renewable energy utilization, and adaptability under various conditions. The results offer valuable insights into the design and operation of multienergy supply systems, potentially fostering the large‐scale implementation of renewable energy systems and leading toward a sustainable energy future.

Co-optimisation of the heliostat field and receiver for concentrated solar power plants

In a concentrated solar power (CSP) tower plant, it is essential to understand the performance of the subsystem formed by the heliostat field and the receiver, operated with an optimal aiming strategy that guarantees the safety and lifetime of the receiver while maximising performance. State-of-the-art studies optimise the heliostat field, aiming strategy and the receiver independently. However, the field and the receiver are interdependent and co-optimisation of the field-receiver subsystem is necessary to obtain the optimal configuration. Fast and accurate annual performance assessments of the subsystem are needed to calculate the annual energy output and the Levelised Cost of Energy (LCOE) of the full CSP system. In this study, a co-optimisation method is proposed based on coupled instantaneous optical, thermal and mechanical models integrated into a system-level model for annual simulation of full system and economics. The resulting system-model is then used for design optimisation based on a genetic algorithm. Several techniques are implemented to make this complex and computationally expensive problem tractable. The proposed method is used to optimise the design of two systems composed of a surround field and a liquid sodium-cooled cylindrical external receiver for first the annual performance and then the LCOE. The good behaviour of the method is confirmed by a sensitivity study. The LCOE-based optimisation leads to a less efficient system than the efficiency-based optimisation but a higher capacity factor. The methods presented are applicable to other CSP plant configurations, including state-of-art molten salt power tower plants.

Optimization of Dimensions of Smooth and Twisted-Tape-Inserted Tubes for Heat Transfer with NaCl/KCl/MgCl2 Molten Salts by Principle of Entropy Generation Minimization

Abstract The entropy generation minimization principle is used as the criterion to optimize the flow and heat transfer of solar collectors and heat exchangers that use molten salts NaCl–KCl–MgCl2 and KCl–MgCl2. The Gnielinski correlation for the Nusselt number versus Reynolds number, as well as the Moody friction factor given by Petukhov, was used for the calculation of the convective heat transfer coefficient and pressure loss due to friction in smooth tubes. For twisted-tap-inserted tube, equations of Nu and friction factor provided by Manglik and Bergles were used. The objective function, the entropy generation rate of the heat transfer system, was expressed as the function of Reynolds number, Prandtl number, heating flux, tube diameter, etc. As a result of the analysis, the optimum Reynolds number was determined and thereby to determine the optimum Nusselt number, convective heat transfer coefficient, friction factor, and tube diameter, which also allows the calculation of optimum flow velocity. The analysis was conducted in the fluid temperature range of 500–700 °C, which covers the operation temperature for supercritical CO2 power cycles in concentrated solar power (CSP) system. Optimized results from the smooth tube and twisted-tap-inserted tube are compared, which is important to the design of solar receivers for CSP systems.

A Review of Radiative Heat Transfer in Fixed-Bed Particle Solar Receivers

A highly efficient receiver is required because re-radiation loss increases dramatically with increased working temperature. Among a large number of receivers, the fixed-bed Particle Solar Receiver (PSR) represents a new pathway to high temperature with maximum overall thermal efficiency. The incoming solar radiation can penetrate deeper into the fixed-bed PSR filled with semi-transparent quartz and ceramic particles (spheres or Raschig rings), resulting in an increased volumetric effect. Reports show that an optimized PSR can realize overall receiver efficiency of around 92% at outlet temperatures above 1000 K, and achieve the annual temperature above 1000 K over 65% annual operating hours integrated with a concentrated solar power (CSP) system. To fully understand radiative heat transfer characteristics and provide deep insight into thermal efficiency, radiation energy is classified as incident solar radiation and radiative heat exchange in two parts. The transfer mechanism, the solution method and the progress of the investigation for each section are summarized and discussed in detail. Then, challenges and future directions, including an innovative design method, an improved experimental approach and an effective simulation method are proposed to put forward this receiver to be a preferred substitute in advanced, high-temperature power cycles.

Impact Assessment of Radiative Heat Transport in ARC-Class Reactor FLiBe Liquid Immersion Blanket

Molten salt systems have become of growing interest in the energy industry due to a wide range of applications (concentrated solar power systems, energy storage, Generation IV fission reactors, and high magnetic field fusion reactors). Because of the high temperature that characterizes such materials, radiative heat transfer (RHT) may become a nonnegligible heat transfer mechanism in molten salt components. In this paper, an investigation of FLiBe RHT has been conducted, with a focus on Affordable, Robust, Compact (ARC)–class fusion reactors, a preconceptual design proposed by Commonwealth Fusion Systems and the Plasma Science and Fusion Center. This class of reactors largely employs FLiBe molten salt due to its thermal and neutronic properties. The reactor is characterized by high temperatures, and its 0.5-m-thick liquid immersion blanket is a component where RHT contribution to the temperature distribution is yet to be evaluated. Therefore, this study is the first work that quantifies the contribution of RHT in ARC-class reactor FLiBe systems. FLiBe optical property spectral-banding assessment is carried out, and the impact of RHT in FLiBe systems is assessed in operational ARC-class scenarios through computational fluid dynamics models by taking advantage of COMSOL® Multiphysics. Heat transfer, thermal-dependent properties, and buoyancy effects are considered in a comparison between scenarios with and without RHT modeling. The flow field in the tank is unaffected by RHT effects, even when considering buoyancy effects. The external layer of the vacuum vessel shows an average decrease in the temperature of 5.4 K and an average decrease in temperature on the surface in contact with the FLiBe tank of 8.1 K. Results indicate that for ARC-class reactors, RHT phenomena are negligible (<1% increase in heat transfer) in operational conditions.

Exergy Analysis and Off-Design Modeling of a Solar-Driven Supercritical CO2 Recompression Brayton Cycle

The latest generation of concentrated solar power (CSP) systems uses supercritical carbon dioxide (s-CO2) as the working fluid in a high-performance recompression Brayton cycle (RcBC), whose off-design performance under different environmental conditions has yet to be fully explored. This study presents a model developed using the Engineering Equation Solver (EES) and System Advisor Model (SAM) to evaluate the operation of two solar-driven s-CO2 RcBCs over a year, considering meteorological conditions in northern Chile. Under design conditions, the power plant outputs a net power of 25 MW with a first-law efficiency of 48.3%. An exergy analysis reveals that the high-temperature recuperator contributes the most to the exergy destruction under nominal conditions. However, the yearly simulation shows that the gas cooler’s exergy destruction increases at high ambient temperatures, as does the turbine’s during off-design operation. The proposed cycle widens the operational range, offering a higher flexibility and synergistic turndown strategy by throttling the mass flow. The proposed cycle’s seasonal first-law efficiency of 39% outweighs the literature cycle’s 29%. When coupled to a thermal energy storage system, the proposed cycle’s capacity factor could reach 93.45%, compared to the value 76.45% reported for the cycle configuration taken from the literature.

Coupled optimization of optical and thermal properties for NaCl-Al2O3 towards efficient thermal energy storage

In this paper, a coupled optimization method of optical and thermal performance was explored by us. The microscopic structure of NaCl-Al2O3 based composite phase change material (CPCM) was established, the thermal properties were obtained by means of molecular dynamics (MD) simulations combined with experiments. The first principle calculations were also carried out to investigate the optical performance of the CPCM. The results indicated that the addition of nano Al2O3 can effectively improve the thermal performance and thermal stability of CPCM, when the mass fraction of Al2O3 nanoparticles in CPCM are 2.2 wt% and 7.2 wt%, the mass loss of CPCM samples were 0.14 % and 0.016 % after 100 times cycle, and the thermal conductivity and specific heat capacity can be increased by 15.45 % and 7.63 % at most. In addition, it was found that the optical performance of the CPCM can be also significantly improved. The microscopic coupled optimization mechanism was successfully revealed by the calculation of phonon density of state and band structures, which is desired to be a candidate approach to improve the photo-thermal conversion efficiency of the heat absorber contained in CSP (concentrating solar power) system.

Thermodynamic analysis of a sorption-enhanced gasification process of municipal solid waste, integrated with concentrated solar power and thermal energy storage systems for co-generation of power and hydrogen

A system of coupled CO2 capture and gasification has led to a new concept entitled sorption-enhanced gasification (SEG) which can increase H2 concentration in the syngas composition. This study proposed a novel configuration of the SEG system comprising concentrated solar power and thermal energy storage systems. Calcium looping (CaL) is utilized as the CO2 capture process. Unlike conventional SEG systems in which calcination heat demand is supplied by an oxy-combustion process, this study considers a heliostat field to provide heat for sorbent regeneration. The solar and thermal energy storage systems are simulated dynamically to achieve accurate results. A steam Rankine cycle is also designed to recover the released heat sources through the SEG system. The overall system performance is explored through energy and exergy analyses. Based on the results, the proposed system managed to produce 0.58 kg/s pure hydrogen in addition to 13.96 MW of net electrical power. Meanwhile, CO2 is captured from syngas composition with capturing efficiency of 95%. The energy analysis shows cold gas efficiency and the annual total energy efficiency of 87.76 and 70.74%, respectively. Based on exergy analysis results, the carbonator reactor exhibits the highest permeance compared to the gasifier and calciner reactors, with an exergy efficiency of 88.74%. Parametric study results show an increase in the cold gas efficiency, hydrogen production rate, and electrical energy efficiency with enhancing steam-to-biomass ratio. An increase in CO2 capture efficiency also improves both the electrical energy efficiency and H2 concentration of the syngas composition. CO2 capture efficiency and S/B ratio are inversely related to the exergy efficiency of the system.

Experimental research on heat transfer characteristic of HITEC molten salt in evacuated tube solar collector

HITEC molten salt (7% NaNO3, 53% KNO3, 40% NaNO2) has been identified as a suitable heat transfer fluid for concentrated solar power (CSP) systems, such as parabolic trough collectors (PTC) and evacuated tube solar collectors (ETSC). In order to optimize the flow and heat transfer performance of HITEC in ETSC, a molten salt heat transfer test rig was built to conduct an experimental study, varying inlet and outlet temperatures and mass flow rates of HITEC. Results show that the heat loss of HITEC in ETSC is lower than the other tubes. The convective heat transfer coefficient of HITEC is much lower than that of HITEC in round tube. Because the experimental data of HITEC in ETSC largely differed from the classical correlation equations, a new empirical heat transfer correlation equation was set for HITEC in ETSC, and the deviation between the experiment data and new correlation was within ±19.2%. Finally, by comparing the inlet and outlet temperatures of ETSC under different irradiation intensities, it is concluded that the ETSC can work stably when the temperature exceeds 700 W/m2.