Thermosyphon Research Articles

The effectiveness of phosphine fumigation of wheat in a farm-scale thermosyphon silo

Fumigation of pests is essential for maintaining the quality of stored grain. Rapid and effective pest control is the key to minimise damage to the valuable grain. The current study investigated the efficiency of a farm-scale thermosyphon silo to passively circulate phosphine fumigant gas by measuring the phosphine concentrations at a series of points throughout the silo. A 50 tonne sealable grain silo with an external thermosyphon was fitted with gas sampling lines at three different levels in the grain body, and also in the headspace. The grain was fumigated with phosphine gas 12 times over a 12 month period to contrast the thermosyphon system efficiency under varied external environmental conditions. The minimum fumigation standards of 200 ppm for 10 days or 300 ppm for 7 days were reached and exceeded in all fumigation cycles throughout the year in 12.5–22 days, demonstrating the effectiveness of the thermosyphon system. In addition, the final fumigation was held until the phosphine concentration dropped to 200 ppm. The silo reached 200 ppm only four days after fumigation, reached a maximum of approximately 600 ppm after 30 days, and did not fall below 200 ppm until 106 days after fumigation. Linear air velocity in the was also measured in the thermosyphon pipe and showed that airflow could reach as high as 2.7 m/s, but flow was sporadic and not consistent, most likely due to pressure build up on the headspace of the silo due to resistance to airflow by the bulk grain body. Temperature and humidity results indicated that while both parameters are fundamental in the production of phosphine from aluminium phosphide tablets, they work against each other. This provides an effective control mechanism that prevents the rapid production of phosphine, thereby reducing the buildup of phosphine and reducing the risk of an explosion.

An experimental evaluation of the performance of a remote 2U loop thermosyphon

In recent years, the increasing application and diversity of electronic systems have resulted in a significant demand for research and development in electronic cooling. Designing and evaluating thermal modules is crucial, especially for systems generating high heat flux levels. This study proposes a novel remote loop thermosyphons (RLTS) for high heat flux applications and cooling 2U servers, which has been assessed experimentally. Additionally, several critical factors are examined, including the filling ratio (FR), air flow rate, and heat load. The experimental study evaluated air flow rates range from 130 to 170 cubic feet per minute (CFM), and the filling ratios span from 40 % to 70 %. The heat load varied from 100 W to 700 W. Compared to the conventional loop thermosyphon, the remote loop thermosyphon exhibited superior performance and sustained higher heat flux. Specifically, this thermal module can effectively manage 640 W at an inlet air temperature of 28 °C with an airflow rate of 170 CFM. Moreover, compared to other available loop thermosyphons, the proposed thermal module demonstrated enhanced heat flux up to 94 W/cm2. These results suggest that the new remote loop thermosyphon is a promising solution for cooling high heat flux applications, such as 2U servers. Furthermore, among all the investigated FR effects the 50 % FR performed better than the other filling ratios. At this filling ratio, the thermal resistance reached a minimum value of 0.078 K/W. The findings indicated that increasing the heat load decreased thermal resistance to a certain threshold, beyond which thermal resistance started to increase. This increase in thermal resistance was caused by restricted space above the evaporator. The confined space effect in a loop thermosyphon system significantly influences the performance and should be considered as a crucial factor in future design endeavors.

Life Cycle Assessment of Thermosyphon and PV Hot Water Systems Under the Same Operating Conditions in a Side-by-Side Experimental Setup in Namibia: Initial Results and Data Comparison with Existing Similar Installations

Life Cycle Assessment of Thermosyphon and PV Hot Water Systems Under the Same Operating Conditions in a Side-by-Side Experimental Setup in Namibia: Initial Results and Data Comparison with Existing Similar Installations

Monitoring and Evaluation of Thermosyphon and PV Hot Water Systems Under the Same Operating Conditions in a Side-By-Side Experimental Setup

Renewable heating and cooling are the primary focus of the Southern African Renewable Heating and Cooling Training and Demonstration Initiative in creating capacity pertaining to this subject. This emphasis is aligned with the United Nation’s 2030 Agenda, which seeks for carbon-neutrality by the year 2030. To address thermal needs on small-scale, thermosiphons systems using evacuated tube collectors, flat-plate collectors, and photovoltaic to heat systems are frequently used. For a scale-up application of these technologies, and for accelerated achievement of carbon-neutrality, a cost-effective technology must be prioritised in various areas of the world with different meteorological conditions. This study therefore intends to establish the technical performance and the cost-effectiveness of these technologies in Namibia’s environment whilst replicating a small-scale house daily hot water demand.

Simulation on the performance and cooling capacity compensation solution of a loop thermosyphon system under fan failure conditions

Fan failure of loop thermosyphon systems (LTS) is a major factor affecting thermal safety of data centers. This paper develops a distributed-parameter model to accurately predict the overall and local heat transfer performance of a loop thermosyphon (the terminal equipment of LTS) under fan failure conditions. The simulation results show that the positions of faulty fans have a significant influence on the evaporator's local airside heat transfer coefficient, but have slight influences on the evaporator's local refrigerant heat transfer coefficient and the condenser's overall heat transfer coefficient, which would not increase the risk of heat transfer performance. Thus, fan airflow rate backup can be used to handle fan failure. Then, the effect of operating parameters including backup airflow rate (Bfan), cold water temperature (Tcw) and increment of cold water flow rate (Im,cw) on the effectiveness and efficiency of the cooling capacity compensation under fan failure conditions is analyzed by using the Taguchi method with an L16 orthogonal array. The Bfan is the primary factor contributing 81.51% on cooling capacity compensation, with Tcw and Im,cw contributing 15.25% and 2.38%, respectively. Considering the energy efficiency, the order of adjustment should be Bfan first, Im,cw second, and Tcw last when fan failure occurs.

Experimental research and energy effectiveness analysis on chip-level two-stage loop thermosyphon system for data centre free cooling

The development of 5G technology has put forward new requirements for computing the abilities of chips, and chip power has also significantly increased. Consequently, the heat load of the rack will increase rapidly in the future. Traditional computer room air conditioning (CRAC) systems cannot satisfy the rack’s high heat flux dissipation requirements, and new cooling forms such as chip-level cooling should be adopted. In this study, a two-stage chip-level cooling system, which is pumpless and waterless, offers flexible and detachable installation based on practical requirements, was proposed. The cooling system removes heat from the chips to the outdoors via two thermosiphon loops, where the heat is first transferred to cold plates tightly attached to the chip surfaces, then transferred through heat exchangers attached to the rack side, and finally dissipated outdoors through air cooling. In this study, a two-stage chip-cooling system was constructed and tested in an enthalpy-difference laboratory. The effects of the liquid filling ratio on the thermal resistance, total temperature difference, and fluid flow pattern under different heat loads were investigated. Second, a heat transfer model for analysing thermal resistance networks was constructed, and the proportions of different types of thermal resistance were determined. Third, an energy-saving analysis of the system is established. The experimental results showed that at single chip heat load 200 W and total heat load 2 kW, the heat transfer temperature difference between chips and outdoors is less than 20 °C at extremely high energy efficiency (cooling load factor reaches 0.05 at outdoor temperature 40 °C), which makes it feasible for free cooling throughout the year in most Chinese areas. The annual PUE in Beijing using the proposed system is 1.15, which indicates a 30 % reduction of the total energy consumption of data centres.

DEVELOPMENT AND INSTALLATION OF SOLAR WATER HEATING SYSTEM FOR FEDPODAM HOSTEL

This paper presents the result of the Development, Installation and Performance evaluation of a 500 liter capacity hot water storage tank with an additional 500 liter capacity cold water storage tank that was, developed, installed and tested at Maryam Abatcha female hostel in the Federal Polytechnic Damaturu, Yobe State, Nigeria which is located at latitude 12.290N and Longitude 11.440E using available materials and thermo syphon principle at an average solar radiation of 630W/m2 to investigate the potential of using solar either directly and indirectly for heating water and to compare its cost with electricity. This design utilized a flat plate collector which was chosen because of the simplicity in construction and ease of maintenance. Two collectors of 1m2 each with single glazing were used as a heat exchanger. The surfaces of the collectors were painted with black paint of absorptivity 0.95 and emissivity of 0.09 to improve its absorption capacity. Readings were taken for a period of nine months starting from March, April, May, June, July, August, September, October and November with minimum ambient temperature of 320C. Maximum hot water temperature inside the tank as 82.30C with an average efficiency of 28.06% in June, with clear sunny atmosphere days and November with lower outlet likely due to cold dusty of the period. Test conducted reveal that the system could satisfy the hot /warm water requirements of the hostel. It was also observed that the water temperature is a function of solar radiation while the cloud cover and dust particles were observed to also affect the performance of solar water heating system thereby reducing its efficiency.

Effect of compact thermosyphon height on boiling curve and thermal performance: A visualization analysis

The thermal management requirement of the servers for data centers has become an urgent issue to be addressed. The two-phase compact thermosyphon has been one of the highly-efficient passive cooling devices to solve heat dissipation problems. In this study, compact thermosyphons with different heights (20 mm, 25 mm, and 50 mm) and filling ratios (25 % − 75 %) were investigated. The corresponding boiling curves and thermal performance were analyzed. Thermal resistance was defined to evaluate the thermal performance in the thermosyphon system. The experimental results illustrate that the reduction in height significantly influences the thermal behaviors of the compact thermosyphon. For the 20 mm height case, the bubble adheres to the condensation surface for a longer time compared with the other cases, which increases the entire bubble growth period. Boiling curves of compact thermosyphons with different heights and filling ratios exhibit distinct characteristics. The heat flux on the boiling surface (qb) with 20 mm height at the low filling ratio (FR = 25 %) is 68.2 % of that with the 50 mm height, indicating the reduced boiling intensity. Both the delayed onset of boiling (ONB) and bubble films of large areas on the condensation surface are generated at FR = 75 % case with 20 mm height, which weakens the phase change heat transfer. For the 50 mm height case, a medium filling ratio and lower input heat flux provide the optimized performance (0.36 K·W−1 of the thermal resistance). For the compact thermosyphon with lower height, low and medium filling ratios are preferred to minimize the deterioration of thermal performance. The outcomes are hoped to provide references for the optimal design and operation of the compact thermosyphon applied in the areas of thermal management and energy conservation.

Study on Effects of Operating Parameters on a Water-Cooled Loop Thermosyphon System under Partial Server Utilization

During the operation of a data center, servers are gradually installed in racks, causing most racks to work under a low heating load for a long time and affecting the cooling efficiency of the loop thermosyphon system (LTS). Thus, the effects of operating parameters on the thermal performance should be investigated. In this study, a water-cooled LTS was experimentally investigated under different airflow rates and heating loads. The results show that the additional liquid refrigerant reduced the heat transfer performance and aggravated a drop in cooling capacity when the airflow rate and heating load were decreased. To further reveal the effects of the operating parameters on the thermal performance and cooling efficiency, a steady-state distributed-parameter model was developed and validated based on the experimental data. The results show that the excessive cooling capacity was reduced by decreasing the airflow rate according to the upper limit of the server exhaust air temperature under partial server utilization. The excessive cooling capacity was reduced by 14.5–52.1% under 5–56.5% server utilization. To further reduce the excessive cooling capacity while ensuring thermal security, the water side operating parameters (including the supply chilled water temperature and water flow rate) were adjusted according to the upper limit of the rack’s average outlet air temperature, which reduced the excessive cooling capacity by more than 23.8% under partial server utilization.

Experimental study on the thermal performance of a novel two-phase loop thermosyphon under low-heat-flux conditions

Two-phase loop thermosyphons are efficient heat transfer components that do not require extra power and can effectively transfer heat over long distances. In this study, two kinds of novel ethanol loop thermosyphons with and without wicks inside their evaporators were fabricated to experimentally investigate the start-up characteristics and thermal performance of the systems under low-heat-flux conditions and with different filling ratios; in addition, there was no height difference between the evaporator outlet and condenser inlet. As a result, temperature overshoot and geyser boiling were evidenced as start-up phenomena specific situations. Both systems failed to transfer heat when the filling ratio was below 30 % because some temperature measurement points were higher than 100 °C, at which point the limits of the experiment were reached. When the heat input was higher than 10 W, the loop thermosyphon with a wick structure could run and stay stable, while the regular loop thermosyphon system stabilized when the heat input was higher than 25 W. The increase in the filling ratio worsened the uniformity of the temperature distribution in the evaporator. The thermal resistance of the system was at its minimum when the filling ratio was 70 %. Both systems had good heat transfer performance when the heat input was high enough.

Investigation of a falling film tube bank heat exchanger with baffle design for water recovery applications

Shell and tube heat exchangers (STHE) are essential thermal equipment and widely used in daily life. A novel thermosyphon system called falling-film thermosyphon (FFTS) is introduced and integrated into STHE system, resulting in a better thermal performance. In this study, a rectangular solid tube bank of FFTS bundles with a baffle design is studied. The numerical simulation for heat and mass transfer of the FFTS heat exchanger is developed to predict the condensation rate of the vapor in the flue gas, and a lab-scale prototype is also built up in COMSOL. The prediction is validated with the experimental data from references, and the model's accuracy is verified within 10%-12% error. Also, the Non-dominated Sorting Genetic Algorithm, version 2 (NSGA-II) is implemented to improve the thermal performance of rectangular tube banks in this paper. Several parameters, e.g., baffle number, tube number, and tube space, are optimized. As a result, compact configurations with more baffles are preferred to enhance the performance associated with a high-pressure drop correspondingly. The optimized layout for the lab-scale prototype can increase by 18 to 32% condensation with a pressure loss of less than 200 Pa.

Mathematical analysis of optimized requisites for novel combination of solar distillers

This study examines the impact of variable Evacuated Annular Tube Collectors (EATCs) on performance, both with and without the use of parabolic concentrators. The study aims to address the irregular use of EATCs by utilizing novel parabolic solar receivers (PSRs) to enhance the performance of the recommended double slope solar still (DSS) in comparison to conventional or PSR-assisted single sloped systems. The DSS-EATC-PSR system has been improved with the inclusion of basin mass temperature (11.4 %) while adhering to a 30° inclination of the basin cover and EATC tubes. An increase in natural thermo siphon circulation has been achieved with improvement of 28.1 % and 0.1 % for DSS-EATC-PSR in comparison to single slope solar still (SSS) with EATC and SSS-EATC-PSR, respectively. The daily energy-exergy efficiencies of the system exhibit a slight decrease of 8.4 % and 4.7 % for overall and exergy, respectively, compared to the conventional solar still system. The daily yield has demonstrated a 4.6 % improvement compared to the SSS system, while maintaining a minimal promotion price of $0.07 per liter. This has been achieved despite a noticeable increase in production cost. The CO2 mitigation results in a higher environmental revenue compared to the SSS system by 5.9 % and 14.6 %. The cost analysis of the DSS system indicates a reduction of 6.6 % in expenses. Additionally, the productivity of the systems has been observed to exceed 100 %, thereby confirming the feasibility of the proposed systems.

Machine learning approach to predict the thermal performance of closed‐loop thermosyphon

AbstractThis paper presents the machine learning (ML) algorithm to predict the thermal performance of closed‐loop thermosyphon (CLT). The experimentation is carried out on the acetone‐charged CLT at different test conditions such as heat inputs, filling ratios, and adiabatic lengths. The test data is used to calculate the performance parameters such as thermal resistance, heat transfer coefficient, and effectiveness of the system. Based on the experimental dataset, the ML algorithms are developed to predict the performance parameters of the CLT system. The ML algorithms such as linear regression, decision tree (DT), random forest (RF), and lasso regression are used for the development of the prediction model. The hyperparameters are well‐tuned and optimized. The prediction measuring parameters (mean absolute error, R2) are analyzed carefully. It is noticed that the DT model outperformed the prediction of the other used models. The R2 score of the DT model was 98.504; whereas, the R2 scores of the RF model and linear regression model were about 94.76 and 92.17, respectively. This study will become a roadmap to the ML approach in the thermosyphon system.

Numerical and experimental investigation of a novel liquid upper-feeding micro-channel flat loop thermosyphon cooling and heat recovery system

ABSTRACT A novel liquid upper-feeding micro-channel flat loop thermosyphon (LUF-MCFLTS) system was developed, to eliminate the drying phenomenon of the upper surface in the traditional LTS and provide a highly efficient solution for DC cooling and heat recovery. The effects of cooling capacity (cooling water flow rate and temperature), heat load, and filling ratio on the heat transfer performance of the LUF-MCFLTS system are investigated experimentally. The results indicated that with the increase in cooling water flow, the decrease in cooling water temperature, and the increase in heat load, the heat transfer performance of the LUF-MCFLTS system was better. Under a heat load of 500 W, a cooling water flow rate of 600 L/h, and a cooling water temperature of 15°C, the heat recovery efficiency could reach 86.28%. Compared with the MCFTS and MCFLTS systems in literature, the recovery efficiency of the LUF-MCFLTS system could be increased by 31.6% and 2.64%, respectively. In addition, an effective numerical model to predict the heat recovery efficiency of the LUF-MCFLTS system with the experimental data in the 2.07% error band has been established. This work provides a new idea and theoretical basis for the design of DC cooling and heat recovery system.

Comparative study on different energy-saving plans using water-side economizer to retrofit the computer room air conditioning system

An energy efficient, environmentally friendly and economical retrofit plan of traditional computer room air conditioning system is necessary to reduce energy consumption of data centers. In this study, two energy-saving retrofit plans, a computer room air handler system with water-side economizer (Plan 1) and a loop thermosyphon system with water-side economizer (Plan 2), are compared with an air-cooled computer room air conditioning system (existing cooling system) in a data center. To analyze and compare the energy efficiency, environmental and economic potential, energy models of the existing cooling system and retrofit plans are established. Under different set points (including supply chilled water temperature and supply air temperature) and 2.08–6 kW average electric power of racks, the free cooling periods of Plan 1 and Plan 2 reach 3878–5867 h and 4541–7661 h, respectively, which lead to the annual energy consumption of Plan 1 and Plan 2 decreases by 27.6–47.3% and 53.4–63.6%, respectively. Due to the lower annual energy consumption of main equipment (including chillers, chilled water pumps, cooling water pumps and terminal equipment), Power Usage Effectiveness of Plan 2 is 0.049–0.090 lower than that of Plan 1, and Global Coefficient of Performance of Plan 2 is 23.3–67.3% higher than that of Plan 1. Furthermore, the annual CO2 emissions of Plan 1 and Plan 2 are 337.3–557.1 tons and 599.8–1106.9 tons less than those of the existing cooling system at different operating stages respectively. Finally, the dynamic payback periods of Plan 1 and Plan 2 are 4.11–5.42 years and 1.64–3.57 years.

An Innovative Design for a Solar Water Heating System Utilizing a Flat-Shaped Heat Pipe

Abstract In this work, an innovative design for a solar water heating system using a flat-shaped heat pipe as a heat transfer device is presented to pave the way for a substantial increase in the thermal performance of these systems. An analytical study is utilized to investigate the thermal performance of the solar water heating system. The analytical results of the flat-shaped heat pipe system are compared with the results of the evacuated tube solar water heating system with a U-tube, thermosyphon, and closed-loop pulsating heat pipe. It is found that the water temperature difference between the inlet and outlet of the flat-shaped heat pipe system is substantially higher than the U-tube, thermosyphon, and closed-loop pulsating heat pipe system by as much as 31.4, 22.5, and 18.5 °C, respectively, at a nominal 0.6 l/min mass flowrate. Furthermore, utilizing the flat-shaped heat pipe in the solar water heating system optimizes the thermal conductivity of the solar setup due to a reduction in the condenser section length. These reductions also lead to a large reduction in the weight and cost of the system.

EVALUATION OF A NOVEL TWO-PHASE CLOSED THERMOSYPHON SYSTEM UTILIZING NiFe2O4/DW, Fe3O4/DW, Fe2O3/DW MAGNETIC NANOFLUIDS

This study concentrates on investigating the implementation of a heat pipe system experimentally and theoretically by simulating a novel heat pipe model employing the MATLAB/Simulink® program, R2021a, using nanofluids obtained by adding 0.5 wt.% and 1 wt.% nickel ferrite, iron oxide, and ferric oxide magnetic nanoparticles to distilled water. A thermal-network dynamic representative was suggested to illustrate the thermal behavior of the heat pipe. The simulated system was capable to indicate the transient demeanour and steady-state temperature of the two-phase closed thermosyphon accurately. The experimental and simulated outcomes demonstrated that the best performance was accomplished using NiFe<sub>2</sub>O<sub>4</sub>/DW magnetic nanofluid with a proper deviation of ± 3.52%. Furthermore, the efficiency, thermal resistance, and Nusselt number of the system were boosted by approximately 22.24%, 9.3%, and 51.9% while utilizing NiFe<sub>2</sub>O<sub>4</sub> magnetic nanofluid corresponding to distilled water at 1 wt.%. A feedback control PID approach is assumed to perform a response within a fraction of a second as well as zero overshoot. The originality of the study is to experimentally and theoretically reveal the thermal behavior of NiFe<sub>2</sub>O<sub>4</sub> containing Ni and Fe and the thermal behavior of the only Fe-containing nanofluid compared to the nanofluids obtained with magnetic particles such as Fe<sub>2</sub>O<sub>3</sub> and Fe<sub>2</sub>O<sub>4</sub>

First Law Comparison of a Forced-Circulation Solar Water Heating System with an Identical Thermosyphon

The main categories of solar water heating systems (SWHSs) are the thermosyphon and the forced circulation (FC). This paper presents an experiment carried out with the aim to compare the energy performance of the FC with a thermosyphon SHWS. Identical SWHSs were installed side by side at the University of West Attica in Athens, Greece. Domestic hot water load was applied to both systems via a microcontroller-based dispensing unit which mimics the demand profile. The trial period comprised the last two months of spring (April and May). For the first law assessment, two energy indicators were utilized: the solar fraction (SF) and the thermal efficiency of the system (ηth). On days with distinctive weather conditions, both systems obtained approximately equal SF and ηth values, without a specific preference between the ambient conditions and the type of SWHS. Regarding a four-day nonstop operation, the FC overperformed the thermosyphon system at both energy indicators. Namely, for the FC and the thermosyphon SWHS, the SF was calculated to be 0.62 and 0.48, and the ηth was 68.2% and 53.3%, respectively.

Simulation of a top-heat-type thermosyphon-based flow stabilization system

Addressing the problem of global warming requires reducing greenhouse gas emissions; thus, considerable efforts are being made to effectively utilize renewable energy. Currently, the conversion efficiency of photovoltaic (PV) panels is approximately 20%, whereas the conversion efficiency of the solar collector exceeds 40%. Therefore, generating hot water with a solar collector is more efficient and cost-effective than using PV panels. Under these circumstances, the effectiveness of a control system in top-heat-type thermosyphon systems to convert the intermittent flow of the circulating working fluid to continuous flow has been established through both indoor and outdoor testing. In this study, a model of the experimental setup involving the top-heat-type thermosyphon is developed, and numerical simulation is performed to investigate the effects of circulating working fluid pressure and pipe friction on intermittent flow. Moreover, the simulation results are compared with those of the experiment with pressure changes. According to the findings, intermittent flow occurs when there is large pipe friction and high pressure. These results attest to the efficacy of the proposed working fluid stabilizing technique.

Experimental investigation for an innovative hybrid photovoltaic/Thermal (PV/T) solar system

An innovative hybrid photovoltaic/Thermal (PV/T) solar system can simultaneously generate both electrical and thermal energy from solar energy. The solar PV panels in the (PV/T) solar system will generate electricity/power efficiently when the loop thermosyphon system (including loop thermosyphons, a heat exchanger, two solenoid valves, an accumulator, etc.) generates thermal energy by absorbing heat from it (solar PV panels). In addition, a decrease in the operating temperature of solar PV panels can increase the electrical efficiency of solar PV panels. In other words, extracting heat from solar PV panels can increase the electrical efficiency of the solar PV panels. In this research, the loop thermosyphon system was used in the innovative hybrid PV/T solar system, and the passive and loop thermosyphon system was used to extract heat from solar PV panels then transfer that thermal energy/heat to water in the shell and tube heat exchanger via latent heat of refrigerant. Consequently, the thermal energy from (warm) water could be used for washing hands, swimming pools, and so on. Furthermore, the loop thermosyphon system was designed without extra pumping power, which is the most crucial advantage of this method. And the loop thermosyphons were attached to the back side of solar PV panels. Finally, solar PV panels’ generated power and electrical efficiency with a loop thermosyphon system are investigated and compared with ordinary solar PV panels without extra cooling through a real-time field measurement/experiment method. The experiment results reveal that (when cooling occurred) the generated power of solar PV panels with the loop thermosyphon system reduced “up to a maximum of about 17%” lower the average operating temperature compared to ordinary solar PV panels; meanwhile, the solar PV panels have loop thermosyphon system increased “up to a maximum of about 7.3%” higher than ordinary solar PV panels during water flow rate into heat exchanger was 0.2 kg/s. The electrical efficiency showed improvement after using/combining the loop thermosyphon system.