Heat Pipe Evacuated Tube Collector Research Articles

Viable-feasibility of innovated combined condenser over traditional individual condenser heat pipe solar evacuated tube water heating system: a comparative-conclusive approach

Purpose This study aims to provide an alternative adoption to overcome the energy crisis and environmental effluence by comparative theoretical and trial testing analysis of an innovative combined condenser unit over traditional individual condenser unit water heating systems. Design/methodology/approach The presented innovative new unit of the combined condenser heat pipe works efficiently through its improved idea and unique design, providing uniform heating to improve the heat transfer and, finally, the temperature of water increases without enhancing the cost. In this design, all these five evaporator units were connected with a single combined condenser unit in such a manner that after the condensation of heat transfer fluid vapour, it goes equally into the evaporator pipe. Findings The maximum temperature of hot water obtained from the combined condenser heating system was 60.6, 55.5 and 50.3°C at a water flow rate of 0.001, 0.002 and 0.003 kg/s, respectively. The first and second law thermodynamic efficiency of the combined condenser heating system were 55.4%, 60.5% and 89.0% and 2.6%, 3.7% and 4.1% at 0.001, 0.002 and 0.003 kg/s of water flow rates, respectively. The combined condenser heat pipe solar evacuated tube heating system promoting progressive performance is considered efficient and environment-friendly compared to the traditional condenser unit water heating system. Originality/value Innovative combined condenser heat pipe evacuated tube collector assembly was designed and developed for the study. A comparative theoretical and experimental energy-exergy performance analysis was performed of innovated collective condenser and traditional individual condenser heat pipe water heating system at various mass flow rate.

Thermoeconomic Analysis of a Solar-Assisted Industrial Process Heating System

Thermal energy in the industrial sector for process heating applications in the range of 50 to 250°C consumes about 35% of the global fossil fuel. Cascaded solar thermal systems are promising solutions to meet clean and uninterrupted thermal energy supply for industrial process heating. Well-engineered cascaded arrangement of solar thermal collector (STC) and photovoltaic thermal (PVT) collector can attain an average solar fraction of more than 50%. In the present research, a solar-assisted process heating system, wherein a STC integrated in series with PVT, has been designed to produce low- to medium-temperature heat at higher solar fractions. Herein, thermal performance and economic viability of this novel system have been investigated and analyzed methodically. In the present research, a comprehensive TRNSYS simulation model is developed and validated experimentally. Results show that PVT integrated with heat pipe evacuated tube collector (PVT-HPETC) and PVT integrated with flat plate collector (PVT-FPC) system can generate thermal energy as high as 1625 and 1420 W with a thermal efficiency of 81 and 77% and exergy efficiency of 13.22 and 12.72%. Levelized cost of heat (LCOH) for PVT-HPETC at process heat temperatures of 60, 70, and 80°C is 0.214, 0.208, and 0.201 MYR/kWh, respectively. It is worth to note that LCOH is less than the existing cost of heat generation which proves that these systems are economically feasible.

Performance enhancement of a solar-driven DCMD system using an air-cooled condenser and oil: Experimental and machine learning investigations

Solar-driven direct contact membrane distillation systems (DCMD) are disadvantaged by low freshwater productivity and low gain-output-ratio (GOR). Consequently, this study aims to achieve two primary objectives: i) improving the solar DCMD performance, and ii) harnessing machine learning models for precise and straightforward modeling of the solar DCMD system. To achieve these goals, a novel solar DCMD system powered with oil-filled heat pipe evacuated tube collectors (HP-ETCs) and equipped with an air-cooled condenser was used for the first time. The system was evaluated under eight different scenarios covering both its energy and economic performances. The performance prediction of three different machine learning models including ANN, SVR and RF was assessed for the proposed system. The results showed that integrating an air-cooled condenser and oil-filled HP-ETCs into the solar DCMD system significantly improved the performance and reduced freshwater cost, resulting in: a 35.39–37 % increase in freshwater productivity; a 30.64–31.57 % enhancement in GOR; a 35–38 % rise in daily efficiency; and a 20 % decrease in freshwater cost. The results demonstrate that ANN and SVR have excellent performance for modeling the solar-driven DCMD system, achieving MAPEtest values of approximately 1 % and 4 % for predicting permeate flux and GOR, respectively.

Energy and the economic estimation of three SWH systems under the Mediterranean climate conditions

This research is focused on the energy estimation of 3-SWH systems installed near each other. Two of them are active systems and the third is a passive one. In these systems are utilized heat pipe evacuated tube collectors with dry connection and flat-plate collectors. With the aim to perform the energy estimation of the systems, the mathematical model is built. Experimental data obtained from their database are used. The recorded data for the three considered solar water heating systems refer to a 1-year time period. Monthly values for the solar irradiation on tilted area of the collectors, temperatures, specific solar yields, and system efficiencies are shown in respective graphs. Referring to the considered climate conditions, where the annual solar irradiation on tilted area of the SWHS collectors is 1499 kWh/(m2·year), it was obtained that the system efficiencies are respectively 41.1 %, 51.6 %, and 51.5 %. To assess the differences between the 3-SWHS, the energy balances for the considered period are built. Also, even the economic estimation based on DPBP and NPV is carried out.

An active solar desalination system integrated with collective condenser heat pipe solar evacuated tube collector: a thermoeconomic analysis.

An experimental investigation was executed on the solar evacuated tube collector containing a collective condenser unit of heat pipe arrangement attached to a single slope solar desalination system. The brackish water preheating was done by the unique solar collector before entering the still. Performance analysis of the system was carried out with 0.001, 0.002 and 0.003kg/s brackish water flow rate in the collector and 0.01, 0.02 and 0.03m of brine water depth in a single-slope solar desalination system. The feasibility of the proposed system was evaluated by thermodynamic analysis, embodied energy, CO2 mitigation and economic analysis. Active desalination system with collective condenser heat pipe evacuated tube collector at 0.001kg/s brackish water flow rate and 0.01m water depth produced maximum freshwater yield, average daily thermal and exergy efficiency of 3.085l/m2day, 30.25% and 3.17% respectively. An increase of maximum freshwater yield of 37.11% and average daily thermal efficiency of 43.5% respectively were achieved at a brackish water flow rate of 0.001kg/s and 0.01m of basin water depth in comparison with a traditional single slope solar desalination system. The embodied energy of the system was estimated as 630.77 kWh, and 0.001kg/s and 0.01m of water depth resulted in the highest earned carbon credit of 16,954.48 INR. The minimum payback period of 2.19years was achieved at the lower brackish water flow rate and basin water depth of 0.001kg/s and 0.01m respectively.

Technical & financial feasibility assessment of heat pipe evacuated tube collector for water heating using Monte Carlo technique for buildings

The main objective of this work is to clear the economic condition of heat pipe based solar water heating technology in India. For this, a techno-economic analysis has been carried out which offers the facts for the investment in this sector. A computation model has been developed by the amalgamation of the Monte Carlo Technique (MCT) and Multi-energy/economic relations that take into consideration the risks and integrated uncertainties of different variables. The results reveal that LCWH and PP are found to be lowest for Zone-V and will require the least collector area. Since the highest solar radiation in Zone-V eventually reduces the ratio of annual energy demand to annual solar radiation. Thus Zone-V is the most favorable place for the installation of the solar water heater. The mean values of LCWH, NPV, and PP are found to be 5.14 INR/kWh, 663788.48 INR, and 5.84 years respectively. However, values of LCWH, NPV, and PP through optimization were found to be lesser by 25–33%, higher by 9–28%, and lower by 37–47% respectively.The MCT is efficient to defeat discrepancies in the results of conventional techniques by taking into consideration the range of states according to their probability to offer more accurate forecasts.

Performance analysis of solar water heater system with heat pipe evacuated tube collector on Moha soft drink industries in Ethiopia

Hot water is a crucial demand for many of Ethiopia's industrial and household heating systems. Most industries are using boilers powered by conventional energy sources to meet the demand for hot water. Due to the environmental impact of conventional energy sources usage and the rise in fossil fuel prices, the utilization of solar energy as a source of energy become a promising candidate for various applications. We use MATLAB/SIMULINK software to carry out this study of solar water heating systems with heat pipe evacuated tube collectors. Comparisons of total solar radiations were made at various optimum tilt angles for the selected locations. The adjustment of tilt angles has a great impact on the collection of useful energy. The maximum average annual energy savings are 1.21E+06 kWh/year for Addis Ababa at monthly and seasonal optimum tilt angles, 1.26E+06 kWh/year for Dire Dewa at a monthly optimum tilt angle, and 1.21E+06 kWh/year for Hawassa at a monthly optimum tilt angle. This means it will reduce 326,700 kg of CO 2 , 340,200 kg of CO 2, and 326,700 kg of CO 2 emissions per year respectively. The efficiency increases as the heat transfer fluid flow rate increases. The maximum annual cost savings are at monthly optimum tilt angles of the collector (6.12E+04 $/year, 6.36E+04 $/year, and 6.11E+04 $/year for Addis Ababa, Dire Dewa, and Hawassa cities, respectively with a payback period of 6.43 years, 6.18 years and 6.44 for Addis Ababa, Dire Dewa and Hawassa cities, respectively.

Real-Time Experimental Performance Assessment of a Photovoltaic Thermal System Cascaded With Flat Plate and Heat Pipe Evacuated Tube Collector

Abstract In response to the global quest for a sustainable and environmentally friendly source of energy, most scientists’ discretion is solar energy, especially solar thermal. However, successful deployment of solar thermal technologies such as solar-assisted process heating (SAPH) systems in medium- to large-scale industries is still in quandary due to their inefficacy in raising ample temperatures. Cascaded SAPH system, which is essentially a series combination of two same or different types of thermal collectors, may provide a worthwhile solution to this problem. In this article, performance assessment and comparison of two cascaded SAPH systems have been presented: photovoltaic thermal (PVT) cascaded with flat-plate collector (PVT-FPC) and PVT coupled with heat pipe evacuated tube collector (PVT-HPETC). Simulation models have been presented for individual FPC, HPETC, and PVT as well as PVT cascaded with FPC and HPETC systems in TRNSYS and validated through outdoor experimentation. Both the first and the second laws of thermodynamics have been employed to reveal veritable performance of the systems. Results show that PVT-HPETC delivers better performance with 1625 W thermal energy, 81.59% energy efficiency, and 13.22% exergy efficiency. It cuts 1.37 kg of CO2 on an hourly basis. Cascaded systems can be effective in sustaining industrial process heat requirements.

The influence of integrated Micro-ZnO and Nano-CuO particles/paraffin wax as a thermal booster on the performance of heat pipe evacuated solar tube collector

The research aims to investigate the possibility of enhancing the functionality of a heat pipe evacuated tube collector (HPETC) with a new method of, one or both an evacuated tube (ET) and two separate storage tanks, incorporating nano or micro-enhanced phase change materials as a thermal energy storage system (TESS). In the proposed systems, the (ET) was filled with enhanced medical paraffin wax, while the two separated tanks were filled with enhanced paraffin wax (grade-A). These two types of paraffin wax were enhanced with 5wt% CuO nanoparticle (NP-CuO) or ZnO microparticles (MP-ZnO). In this study, Six tests were carried out to do the investigation. Three tests were done to investigate the effect of the integration of enhanced-PCM in the only (ET) of HPETC. While the other three tests performed to investigate the effect of enhanced-PCM integrated into both (ET) of HPETC and two additional storage tanks. The main advantage of this new system is that it improved solar water heater efficiency by minimizing hot water temperature fluctuations. Thereby, the efficiently thermal isolation of the (ET) and storage tanks and the efficient energy accumulation in PCM which enables the system to supply hot water even when there is no solar radiation at night or in overcast weather. The results showed that the integration of enhanced-paraffin wax with NP-CuO and MP-ZnO in both the (ET) and the separated tanks gives an efficiency improvement range of (36.8-50%) and (25.43-41.4%) respectively, While the integration of enhanced-paraffin wax with NP-CuO and MP-ZnO in the only (ET) led to an increase in the efficiency with a range of (33.8-45.7%) and (23.8-26.7%) respectively, compared with a typical reference collector without PCM. Also, the NP-CuO enhanced paraffin wax integrated with the ET gave a better improvement in the evaporation & condensation coefficients in the evaporator and condenser sections where their values were (401 and 2366.4 W/m2·°C) respectively at a flow rate of 1L/h.

Long-Term Performance of Anti-Freeze Protection System of a Solar Thermal System

In a moderate, transitory climate, to prevent freezing of outdoor pipes and collectors in solar thermal systems, anti-freezing fluids are commonly used. There is little experience of using water without any additives as a solar thermal fluid in such a climate. Based on these findings, to fill the knowledge gap this article presents the long-term results of thermal performance and anti-freeze protection of a solar heating system with heat pipe evacuated tube collectors with water as a solar thermal fluid. The operation of this system under real conditions was analysed for five years in southern Poland. The annual value of solar insolation ranged from 839 to almost 1000 kWh/m2. The monthly efficiency of the solar collectors from March to October was usually higher than 25%, and the lowest was between November and January. The anti-freeze protection system consumed annually from 7 to 13% of the heat generated by the collectors in the installation. Supporting the operation of the central heating system in the building during the winter season highly improved the efficiency of the solar collectors. Results show that it is possible to use water without any additives as a solar thermal fluid in a moderate, transitory climate.

Energy and Economic Estimation for a Passive Solar Water Heating System Equipped with a Heat Pipe Evacuated Tube Collector:

The energy and the economic estimation for a passive solar water heating system under the Tirana climate conditions is performed. The trial system includes a heat pipe evacuated tube collector. To fulfil these objectives, measured values recorded every minute from the data logger of the system are used. The studied solar collector has a slope of 45° and is oriented 10° East from the South direction. The heat pipe evacuated tube collector has an aperture area of 1.476 m2. For an annual time period the irradiation on tilted solar collector area, the extracted energy from the storage tank, the delivered energy to the thermal consumer and the system efficiency were defined. Also, the economic assessment of the system is performed.

Energy and Economic Estimation for a Passive Solar Water Heating System Equipped with a Heat Pipe Evacuated Tube Collector:

The energy and the economic estimation for a passive solar water heating system under the Tirana climate conditions is performed. The trial system includes a heat pipe evacuated tube collector. To fulfil these objectives, measured values recorded every minute from the data logger of the system are used. The studied solar collector has a slope of 45° and is oriented 10° East from the South direction. The heat pipe evacuated tube collector has an aperture area of 1.476 m2. For an annual time period the irradiation on tilted solar collector area, the extracted energy from the storage tank, the delivered energy to the thermal consumer and the system efficiency were defined. Also, the economic assessment of the system is performed.

Performance Analysis of Flat Plate and Evacuated Tube Collectors

This study gives a thermal analysis on the effect of operating parameters on the performance of solar water heating systems with two distinct collector configurations; flat plate and heat pipe evacuated tube collectors. The thermal analysis of these two systems was conducted based on the account of variation in weather conditions of Adama and volume flow rate, using T*SOL® Simulation software, to study the impact of these operating conditions on the system efficiency, system solar fraction, storage tank outlet temperature, collector outlet temperature, energy accumulated and collected in the tank and collector. This is done to compare the performance of these two systems with each other, based on thermal analysis in order to provide the necessary information required to select the most appropriate solar collector and its operating conditions. The results showed that for a fluid circulating at 120 l/h, the highest monthly solar fraction of FPC and ETC systems were 80% and 64.6%, respectively, around November with a total solar irradiation of 191 kWh/month. For both systems, the hourly tank outlet temperature peaked in November to 87 °C and 71.2 °C for ETC and FPC, respectively. For a typical day in April, the maximum tank outlet temperature becomes 74 and 62.5 °C. Regarding the flow rate, simulation of the systems is done for three flow rates (80, 120 and 160 l/h). The results also showed that for a typical day in April, the hourly maximum tank inlet-outlet temperature difference was obtained for both ETC and FPC at 12:00 PM at a flow rate of 160 l/h, where the corresponding maximum tank outlet temperature becomes 74 and 62.5 °C. At this volume flow rate, a solar water heating system efficiency of 59% and 50%, and also a system solar fraction of 82% and 68.1% could be achieved for a SWH system employing ETC and FPC, respectively. Overall, ETC systems proved to be a more efficient system to satisfy the need of hot water.

Thermodynamic and techno-economic analysis of heat pipe ETC water heating system for Indian composite climate

This paper presents the thermodynamic and techno-economic performance calculation of heat pipe evacuated tube collector (HP-ETC) solar water heating system by energy, exergy analysis and different economic parameters for Indian composite climate of Jammu. The HP-ETC solar water heating system of 1.69 m2 was designed and fabricated for a family with an average size of six persons. The experiments were done for six different mass flow rates of working fluid (water) such as 20, 30, 40, 50 and 60 L per hour (LPH). The highest average energy and exergy efficiencies were obtained to be 72% and 5.2%, respectively, for 20 LPH, while the lowest values of respective parameters were 55% and 1.25% at 60 LPH flow rate. The maximum and minimum average outlet temperatures from collector were found to be 76.4 and 45 °C at 20 and 60 LPH, respectively. It has been observed that heat pipe ETC water heating system is better than direct flow evacuated tube collector-based water heating system. Also, the exergy efficiency was found to be much lower than energy efficiency for all the selected mass flow rates. The techno-economic analysis of heat pipe evacuated tube solar water heating system was done by three methods, namely annual cost, life-cycle savings and payback period. The cost of hot water production at desired temperature was found to be INR 0.12 per liter, whereas that of the electric geyser and gas geyser was INR 0.40 and 0.26, respectively. The payback period of heat pipe ETC solar water heater was estimated to be 4 years, which is much less than the life of HP-ETC solar water heating system.

Energy performance analysis of a forced circulation solar water heating system equipped with a heat pipe evacuated tube collector under the Mediterranean climate conditions

This work represents the energy performance analysis during the annual time period of a forced circulation solar water heating system equipped with a heat pipe evacuated tube collector having an aperture area of 1.476 m2 under the Mediterranean climate conditions. For the purpose, recorded data from a field-trial installation are exploited. The recorded data obtained every minute are used to perform the energy analysis during an annual period. The analysis is performed by using mathematical models and by representing the results for each month. Monthly values of measured parameters and calculated quantities offered a clear view regarding the operation of the considered field-trial installation for this climate region. For an annual irradiation on solar collector plane of 2,212 kWh/year, it was noticed that the annual useful heat gain for the heat pipe evacuated solar tube collector, the useful energy delivered by the solar circuit to the storage tank, and the delivered energy to the thermal consumer were 1,345 kWh/year, 1,311 kWh/year, and 1,009 kWh/year, respectively. The annual efficiency for the heat pipe evacuated solar tube collector was 0.62, while for the forced circulated system was 0.516. Also, the annual energy balance of the system obtained from the calculation is built.

Comparison of the Energy Performance between Flat-plate and Heat Pipe Evacuated Tube Collectors for Solar Water Heating Systems under Mediterranean Climate Conditions

Comparison of the Energy Performance between Flat-plate and Heat Pipe Evacuated Tube Collectors for Solar Water Heating Systems under Mediterranean Climate Conditions

Hydronic heated pavement system performance using a solar water heating system with heat pipe evacuated tube solar collectors

In this paper, a solar water heating system (SWHS) with heat-pipe evacuated tube collectors (HP-ETC) is experimentally evaluated as a hydronic heated pavement system heat source. Outdoor testing in Fayetteville, Arkansas was performed over the 2017–2018 winter season. The data collected in this study were used to evaluate pavement heating and snow-melting performance. A dual automated thermostat heating system was incorporated to (1) control pavement heating operation to maintain an anti-icing surface temperature (2 °C), and (2) control direct fluid heat transfer from the HP-ETC to the storage tank. Results showed that the SWHS with HP-ETC provided adequate thermal energy to maintain two 3.05 m × 1.22 m × 0.13 m concrete slab surfaces above freezing temperature. During a 6 h man-made snowfall test, the pavement maintained a snow-free surface. The maximum storage tank fluid temperature recorded was 74.0 °C during the test period. In clear sky conditions, the HP-ETC collected an average daily power of 2.7 kW.

Multiphase numerical analysis of heat pipe with different working fluids for solar applications

Energy crisis is a prognosis predicted in many cases with the indiscriminate encroachment of conventional energy sources for applications on a massive scale. This prediction, further emboldened by the marked surge in global average temperatures, attributed to climate change and global warming, the necessity to conserve the environment and explore alternate sources of energy is at an all-time high. Despite being among the lead candidates for such sources, solar energy is utilized far from its vast potential possibilities due to predominant economic constraints. Even while there is a growing need for solar panels at more affordable rates, the other options to harness better out of sun’s energy is to optimize and improvise existing technology. One such technology is the heat pipe used in Evacuated Tube Collectors (ETC). The applications of heat pipe have been gaining momentum in various fields since its inception and substantial volumes of research have explored optimizing and improving the technology which is proving effective in heat recovery and heat transfer better than conventional systems. This paper carries out a computational analysis on a comparative simulation between two working fluids within heat pipe of same geometry. It further endeavors to study the multiphase transitions within the heat pipe. The work is carried out using ANSYS Fluent with inputs taken from solar data for the location of Vellore, Tamil Nadu. A wickless, gravity-assisted heat pipe (GAHP) is taken for the simulation. Water and ammonia are used as the working fluids for comparative multiphase analysis to arrive at the difference in heat transfer at the condenser section. It is demonstrated that a heat pipe ETC with ammonia as working fluid showed higher heat exchange (temperature difference) as against that of water as working fluid. The multiphase model taken aided in study of phase transitions within both cases and supported the result of ammonia as fluid being a better candidate.

Effect of a low cost parabolic reflector on the charging efficiency of an evacuated tube collector/storage system with a PCM

This paper presents a novel concept of using a phase change material (PCM) to store thermal energy directly within a heat pipe evacuated tube collector equipped with a compound parabolic concentrator (CPC). The excellent insulating properties of evacuated tubes and the use of latent heat are significant advantages of a PCM integrated evacuated tube collector/storage (ETC/S) over traditional solar water heaters. However, during the charge cycle of the ETC/S, direct solar radiation only reaches the exposed area of the evacuated tubes, which results in uneven heating of the PCM due to a lower energy input in the shaded area. This can be prevented by using a CPC to concentrate the solar radiation on the shaded area of the evacuated tubes, thereby raising the temperature of the PCM and quantity of stored heat. Therefore, a polished, thin aluminum sheet was used as low cost CPC with a concentration ratio of 1.2x. Technical grade paraffin with an onset melting temperature of 51.24°C was used as the PCM. The results from this study showed that the application of the CPC caused the temperature of paraffin on the shaded side of the evacuated tubes to increase more rapidly, especially during and after melting of the paraffin. Furthermore, the use of a CPC in a PCM integrated ETC/S improved the average gross charging efficiency from 31% to 36% and the maximum charging efficiency from 40% to 49%.

Energy-exergy analysis of a multipurpose evacuated tube heat pipe solar water heating-drying system

The current study was aimed to design, manufacture and examine a solar heating-drying system experimentally. The heat pipe evacuated tube collector in this system, in addition to supplying the required energy for water heating, supplied the energy needed for a dryer. Moreover, a water heat recovery system was considered for the dryer to enhance the overall efficiency of the system and to make maximum use of solar energy intake. Also, a mathematical model was developed for the energy and exergy analysis of the collector as well as validation with experimental results. In order to simulate the hot water consumption, the consumption pattern of a students’ dormitory hall was used for the case study. The given system was tested under the weather conditions of Sanandaj city and the obtained results indicated the effectiveness of the heat recovery system. The findings showed the optimal number of collector pipes to be 15. Fluctuations of fluid temperature during hot water discharge and replacement with cold water caused fluctuations in collector outlet fluid temperature. Also, a direct association was observed between hot water consumption pattern and system performance. The changing trend of exergetic efficiency was ascending over time. At the end of the day, this efficiency reached its maximum level, about 10.6%. The performance of exchanger was highly dependent upon the ambient temperature and in the volumetric flow rate of 0.0328m3/s, the maximum outlet air temperature of dryer was about 45.5°C. Also, maximum use of the auxiliary system was reported in the early morning (1.5h), which was reduced over time. After 14:00pm, the solar system was able to supply the required energy for the system individually. Finally, the findings of regression analysis showed the most accurate equation for expressing the effectiveness of the dryer as a function of environmental and functional parameter of x (which is equal to (Tw,i−Tamb)/G) expressed as ε=112.21x3−47.095x2+5.8257x+0.1139.