Radiant Floor Heating System Research Articles

Optimization of the configuration and flexible operation of the pipe-embedded floor heating with low-temperature district heating

The radiant heating is cost effective way of space heating while providing favourable thermal comfort. Due to the large thermal flexibility, it is possible to utilize the pipe embedded radiant heating for low-temperature heating and demand management, thereby giving more access to the low-grade heat sources such as the renewable energy or the industrial waste heat. In this study, we investigate the optimal configuration of the radiant floor heating system considering different district heating (DH) scenarios. We propose the scheduled control strategy considering the comfort requirements, the occupancy and the dynamic energy price. Parametric simulations regarding the pipe spacing, the thickness of the concrete core, and the DH supply temperatures are performed by Modelica models. The critical levels of the radiant floor configurations of applying medium-temperature DH (MTDH), low-temperature DH (LTDH) and ultra-low temperature DH (ULTDH) are investigated. The indoor comfort, the thermal performances, the economy performances and the energy flexibility as the crucial factors of different cases are analysed and compared. The results show that the pipe spacing of 300 mm achieves better comfort and shorter charging time for all DH scenarios of the case nearly zero energy building (NZEB). The larger thickness of the concrete core can stabilize the indoor temperature variation and buffer the impact from the environmental disturbance more effectively.

Enhanced thermal performance of Na2HPO4·12H2O composite phase change material supported by sepiolite fiber for floor radiant heating system

The application of phase change materials (PCMs) with latent heat storage characteristics in building system can coordinate the imbalance between energy supply and demand by absorbing excess heat, thereby achieving the overall energy consumption reduction. In this study, a novel kind of composite PCM (CPCM) composed of modified Na2HPO4·12H2O and sepiolite fiber (SEP) is developed. It is shown that adding 4 wt% of α-Al2O3 and 1.5 wt% of sodium alginate (SA) can reduce the supercooling degree of Na2HPO4·12H2O from 18.4 °C to 1.0 °C. The obtained PCM mixture is absorbed into SEP to fabricate form-stable composite PCM at a loading of 60 wt%, which has a melting temperature of 35.7 °C and a high latent heat of 127.8 kJ kg−1. The composite processes good thermal reliability and a moderate thermal conductivity of 1.069 W m−1 K−1. Furthermore, thermal performance of the CPCM is evaluated by combining a floor radiant heating system with CPCM layer in a small testing room. It is found that the average central temperature of the testing room with CPCM floor can be increased by 3.1 °C compared to that of the reference room. Besides, the thermal comfort time of indoor air temperature in CPCM room can be up to 252.5 min longer. The better thermal regulation performance of the CPCM floor is attributed to its suitable phase change temperature and high latent heat. The results indicate that the obtained CPCM can be employed into floor system for building energy conservation purpose.

Effect of Wood Properties and Building Construction on Thermal Performance of Radiant Floor Heating Worldwide

Due to its relatively lower thermal conductivity, the suitability of wood is called into question when selecting the flooring material best suited to radiant heating systems. The European standard EN 1264 considers floorings with a thermal resistance over 0.15 m2 K/W to be out of scope. This belief was partially disproved in a previous article that studied wooden floors for Madrid’s climate. However, the effect of climate still needs to be addressed. The present study extends the previous research to worldwide climates and aimed to answer the following questions: (1) Do the lowest thermal conductivity woods present good thermal performance when used in radiant floors? (2) Should the flooring have a maximum thermal resistance value? (3) Is the standard thermal resistance limit of 0.15 m2 K/W objectively justified? And (4) Do the answers of the preceding questions depend on the climate and the construction characteristics? To answer these questions, 28 cities were selected according to the Köppen–Geiger climate classification. In each city, 216 different dwellings were simulated with 60 wood floorings and one of low thermal resistance as a reference, comprising a total of 368,928 cases. Thermal performance was evaluated in terms of three parameters: energy demand, thermal comfort, and start-up lag time. Consequently, the answers to the previous questions were: (1) The lowest thermal conductivity woods can be used efficiently worldwide in radiant floor heating systems with start-up lag times close to that of the reference flooring; (2) There is no limit value for thermal resistance for floorings that can be applied to all dwellings and climates; (3) No objective justification was found for establishing a thermal resistance limit for flooring of 0.15 m2 K/W; and (4) Climate and construction characteristics can play an important role in the correct selection of flooring properties, especially in severe winters and dwellings with the greatest outdoor-exposed envelope and the worst insulation.

Numerical and experimental study on a concrete slab behavior in steady periodic state in presence of metal cylinders perpendicular to the slab surface

The well established interest in underfloor heating systems has grown in recent years mainly due to the possibility that these systems offer to be supplied with water at low temperatures, therefore with renewable sources or similar to them (solar energy, heat pump, cogeneration). This advantage and these systems performance can be improved by increasing the thermal conductivity of everything inserted between the pipes in which hot water flows and the indoor environment/ambient. In a previous work a mortar slab with embedded metal cylinders has been studied, to evaluate the conductivity increase due to the metal elements presence. Moreover, the slowness in response to the regulation system actions, necessary to maintain the desired environmental conditions as the heating loads vary, is considered a radiant floor heating system fault; in this paper this aspect has been investigated. A numerical study and an experimental investigation have been conducted, to evaluate the mortar thermal inertia variation due to the presence of metal cylinder elements embedded in the slab. Resultsshow that the time-costant Cτ value is reduced up to 75% compared to pure mortar, and a lower amplitude reduction (damping) on the opposite face of the slab is observed, making this mortar with metal elements a good solution for radiant floor equipments.

Thermal behavior evaluation of a radiant floor heating system incorporates a microencapsulated phase change material

The rapid growth of urbanization and the increase of internal comfort requirements impact negatively the environment and the energy consumption of the building sector. Therefore, it becomes very crucial to provide an internal thermal comfort with environmentally friendly techniques. In cold regions, the heated floor incorporates a phase change material is an outstanding technique that can ensure high thermal performance and meet the thermal comfort requirements of occupants. In the present study, the thermal performance of a heated floor impregnates a microencapsulated PCM was numerically studied and evaluated. The heated floor system consists of tubes where hot water circulates, buried under the ground made up of different layers. The thermal waves rise from below heat up the ground which in turn transmit the flow recovered. The integration of a PCM in the floor mainly aims to benefit from its considerable storage ability in order to reduce the energy consumption of the heating system and stabilizes internal temperature around the set temperature of comfort in a long time. To evaluate the PCM under-floor heating system a physical model based on two-dimensional computation is used. The calculations are made by considering the enthalpy approach and applying the numerical finite volume method. The effect of different parameters such as microcapsules integration, mass fraction, tubes inter-distance and PCM type on the heated floor thermal performance are evaluated and discussed. The obtained results show that the best performance of the heated floor is got when 15% of microcapsules are placed above the heating tubes. Consequently, an increase of 4 °C in the amplitude and a phase shift of 5 h 30 min compared to the base case (heated floor without PCM) are obtained.

Field research on the trinity energy storage and heating system of villa in cold area

Since the implementation of changing coal into clean energy heating in the Beijing–Tianjin–Hebei region, there has been a tremendous change in terms of air quality during the winter in the north. On the basis of field research for resort sample room setting up in the Yanqing district , Beijing, this paper mainly expounds the cold and heat sources and system solutions used by resort villas to meet the needs of hot water, heating, and cooling throughout the year, and introduces a new type of solar energy ‘The heat pump direct floor radiant heating system’ (called “Trinity”), which can combine air source heat pump-solar system and direct floor radiant heating to ensure the efficient and stable operation of the heating system while making full use of solar energy. Moreover, with the combination of modeling analysis on the annual load via DeST software, the result of actual measurement sees “Trinity” system as the optimal solution not only by means of comparing the heating scheme of the original single air source heat pump unit and the solar energy + air source heat pump unit’s simulation comparison, it was concluded that the initial investment of scheme two was 16,969 yuan and the initial investment of scheme two was 17,352 yuan. The annual operating cost of the second option is 3577.8 yuan, and the annual operating cost of the second option is only about one-half of the annual operating cost of the second option. Based on the calculation of the investment recovery period, the cost savings of the second option after only 0.15 years is net income. Therefore, the “Trinity” scheme is selected as the best scheme.

Thermal response time prediction-based control strategy for radiant floor heating system based on Gaussian process regression

One of the main obstacles to wider applications of radiant floor heating systems with great thermal comfort and energy efficiency is the long response time caused by large thermal inertia and little research has been conducted to effectively address this issue. In this study, an optimal control strategy based on a thermal response time prediction model for radiant floor heating systems was proposed by applying the gaussian process regression (GPR) algorithm. First, a comprehensive database of the thermal response time for various scenarios based on different building configurations, radiant floor, and weather characteristics was obtained by parametric simulations after base-case building validation. Then a sensitivity analysis of the response performance of the seven explanatory variables by Pearson correlation coefficients was conducted and a theoretical explanation was provided. Besides, the response time prediction model based on the GPR algorithm with a larger R2 of around 0.96 was obtained by an in-depth comparison with commonly used machine learning algorithms such as multiple linear regression, random forest, and support vector machines. Its accuracy was verified by cross-validation and a 25% database. Finally, an optimal control strategy based on the response time prediction model was proposed which can reduce the response time from 96 ∼ 188 mins to 44 ∼ 75 mins, achieving a reduction of 41% ∼ 64% while keeping the comparative power consumption. Therefore, the proposed optimal control strategy can effectively reduce the thermal response time of radiant floor heating systems and improve the indoor thermal comfort during the thermal response phase without sacrificing power consumption.

Preparation and thermal performance enhancement of sodium thiosulfate pentahydrate- sodium acetate trihydrate /expanded graphite phase change energy storage composites

Heat energy storage using phase change materials (PCMs) in electric radiant floor heating system (ERFHS) is a favorable solution to the improvement of energy efficiency. In this paper, the sodium thiosulfate pentahydrate (Na2S2O3•5H2O,STP)- sodium acetate trihydrate (CH3COONa•3H2O, SAT) eutectic mixture was prepared by adding 30 wt.% STP and 70 wt.% SAT. Sodium carboxymethyl cellulose (CMC) and sodium pyrophosphate (Na4P2O7,TSPP) were added to fabricate the modified STP- SAT phase change material. The results showed that almost no phase separation occurred in STP- SAT eutectics with 1 wt.% CMC and 0.4 wt.% TSPP, and its supercooling degree was reduced to 0.3 °C. The thermal properties of the composite phase change material (CPCM) with different contents of expanded graphite (EG) were studied. And the experimental results showed that the composite containing 8% EG displayed a high phase change enthalpy (186.0 kJ/kg) and an ignorable supercooling degree. The addition of EG increased the thermal conductivity of STP-SAT from 0.748 to 2.92 W/m•K. The thermal reliability of CPCM was confirmed through the thermal cycle test and thermogravimetric analysis (TGA). After 200 thermal cycles, CPCM exhibited fantastic thermal stability and reliability.

Effects of different environment combinations on the comfort and productivity of researchers in winter

Indoor environmental quality is considered an important indicator of the sustainable development of architecture. It not only reflects the comfort level of occupants in the building but also affects their productivity, particularly in research institutions. However, due to the inherent correlation among various environmental indexes, it is difficult to evaluate the influence of specific physical parameters on the occupant’s comfort and research performance. This paper is based on an experiment conducted in a controlled research office in a pharmaceutical research company in the Northeast of China. The controlled research office was equipped with a radiant floor heating system that supplied heating in winter. We recruited 32 researchers and divided them into four subgroups. Each subgroup of researchers was required to conduct daily research activities under 12 different environment combinations. Data were collected from physical environment measurements, questionnaire surveys and performance tests. The results reflected that under the condition of radian floor heating in winter, changes in thermal, visual and acoustic environments could have a significant influence on occupants’ satisfaction with the environment. However, the research performance was affected only by thermal and acoustic conditions. There was a weak correlation among thermal, visual, acoustic and indoor air quality comfort.

Influence of Wood Properties and Building Construction on Energy Demand, Thermal Comfort and Start-Up Lag Time of Radiant Floor Heating Systems

Radiant floor heating is becoming increasingly popular in cold climates because it delivers higher comfort levels more efficiently than conventional systems. Wood is one of the surface coverings most frequently used in radiant flooring, despite the widely held belief that in terms of thermal performance it is no match for higher conductivity materials if a high energy performance is intended. Given that the highest admissible thermal resistance for flooring finishes or coverings is generally accepted to be 0.15 m2K/W, wood would appear to be a scantly appropriate choice. Nonetheless, the evaluation of the thermal performance of wooden radiant floor heating systems in conjunction with the building in terms of energy demand, thermal comfort, and start-up period, has been insufficiently explored in research. This has led to the present knowledge gap around its potential to deliver lower energy consumption and higher thermal comfort than high-thermal-conductivity materials, depending on building characteristics. This article studies the thermal performance of wood radiant floors in terms of three parameters: energy demand, thermal comfort, and start-up lag time, analysing the effect of wood properties in conjunction with building construction on each. An experimentally validated radiant floor model was coupled to a simplified building thermal model to simulate the performance of 60 wood coverings and one reference granite covering in 216 urban dwellings differing in construction features. The average energy demand was observed to be lower in the wood than in the granite coverings in 25% of the dwellings simulated. Similarly, on average, wood lagged behind granite in thermal comfort by less than 1 h/day in 50% of the dwellings. The energy demand was minimised in a significant 18% and thermal comfort maximised in 14% of the simulations at the lowest thermal conductivity value. The vast majority of the wooden floors lengthened the start-up lag time relative to granite in only 30 min or less in all the dwellings. Wood flooring with the highest thermal resistance (even over the 0.15 m2K/W cited in standard EN 1264-2) did not significantly affect the energy demand or thermal comfort. On average, wood flooring lowered energy demand by 6.4% and daily hours of thermal comfort by a mere 1.6% relative to granite coverings. The findings showed that wood-finished flooring may deliver comparable or, in some cases, higher thermal performance than high-conductivity material coverings, even when their thermal resistance is over 0.15 m2K/W. The suggestion is that the aforementioned value, presently deemed the maximum admissible thermal resistance, may need to be revised.

Experimental and Numerical Study on Thermal Performance of a Novel Direct Expansion Air-Source Heat Pump Heating System

In this paper, a novel direct expansion air-source heat pump heating system with a gravity-driven radiator as a heating terminal was developed, for the purpose of reducing the energy consumption and improving the thermal comfort of indoor personnel. The thermal response speed of the system at the start-up stage was experimentally studied firstly. The results showed that the thermal response speed of the developed system was slightly lower than that of a traditional air-source heat pump heating system with a convective heating terminal, but largely higher than that of an air-source heat pump floor radiant heating system. When the outdoor air temperature fluctuated between −5.2℃ and −1.0℃, the average rising ratios of indoor air temperature at the start-up stage for the developed heating system and the traditional system are 10.8℃/h and 13.8℃/h respectively. On this basis, an optimization study was then conducted to further improve the thermal performance of the developed heating system. The numerical results indicated that integrating a cross-flow fan to the gravity-driven radiator is able to promote the thermal performance of the heating system obviously at the start-up stage, because the convection heat transfer of the radiator was highly enhanced. Among the simulation conditions, the time required for the air temperature at head height to reach the designed temperature is shortest when the flow angle of the fan is 0° with an air speed of 0.6 m/s. while setting the flow angle of the fan to −45° with an air speed of 0.4 m/s is recommended to achieve the most thermal comfort for the whole body.

Heating performance of heating floor integrated with impinging jet ventilation system

Radiant floor heating systems provide comfortable indoor thermal environment. Primary air supply systems can be used to remove contaminants in the space heated by radiant floor. In this study, heating performance of integrated system of impinging jet ventilation (IJV) and heating floor was numerically investigated. The lowest floor heating capacity was 0 W/m2 and gradually increased to 50W/m2, and the primary air temperature supplied by IJV were 14, 16 and 18°C, respectively. In terms of contaminant removal efficiency, contaminant removal efficiency (CRE) was applied. The vertical dimensionless temperature distribution was used to analyse the heating performance of HF on supply air. The numerical results showed that the supply air layer of IJV could be heated by 60% to 80% under the heat effect of HF. The same is true for low supply air temperature 14 °C. The integrated system IJV/HF generated the weaken thermal stratification which is beneficial for energy saving. The CRE of IJV/HF system was influenced by the downward airflow of external wall. Sufficient supply air could overcome the downflow and effectively increase the CRE value (> 2).

발열유리 창호시스템의 발열량에 따른 실내공간 열적 쾌적성능 분석

Purpose: In this study, an approach using the heated glazing window system as an auxiliary heating system is evaluated in terms of thermal comfort. Heat loss through window parts can occur relatively high because of low thermal resistance, which causes keeping lower surface temperature of the window, typically when outdoor air temperature is lower. With such issues, occupants may feel thermal discomfort near window parts mainly due to the radiant temperature asymmetry. In this study, an approach using the heated glazing window system as an auxiliary heating system is proposed to improve the performance of occupant‘s thermal comfort in a conditioned room. Method: For this analysis, a floor radiant heating system is considered as the main heat supply system in the conditioned zone. The internal thermal information of the room is calculated using a two-dimensional heat transfer analysis simulation (i.e., TRISCO). To quantitatively analyize the thermal comfort of the space adjacent to the window, the Predicted Mean Vote(PMV) at each point is derived by dividing the internal space into a two-dimensional grid. Result: As a result of the analysis, it was found that the heated glazing window system contributes to making the indoor thermal comfort uniform and can improve the thermal comfort of the window adjacent area. The maximum PPD deviation of the indoor space is about 6.3% when the heated glazing system is not operated, 1.8% under the heating of 20W/㎡, and 0.08% under the heating of 40W/㎡

Generic mathematical formulation of the total heat transfer coefficients between heated radiant floor surfaces and rooms

In radiant floor heating systems, the total heat transfer coefficients (THTCs) of floor surfaces represent a key parameter for design and performance calculations. A small change in the THTC exerts a non-negligible effect, but the THTC values or formulas given in the literatures are different. Moreover, no study has explained this phenomenon thus far. Therefore, the selection of THTC values is relatively subjective in practical engineering. In the context of promoting energy savings and realizing carbon neutrality as soon as possible, further research must investigate THTCs. On the based of the principle of heat balance, a generic calculation model of the THTCs is proposed, and its accuracy is verified with experimental data. The influence of each parameter on THTCs is analyzed and unified as the influence of temperature difference. Then, the improved formula is obtained, and its adaptability and accuracy are verified with experimental data from two studies. Results show that indoor design temperature greatly affects THTCs. The reason behind the different THTC formulas given in existing studies is also discovered. Given the same indoor design temperature, the relationships between THTCs and temperature differences caused by different parameters follow the same trend line. Only the improved THTC formula shows a good agreement with the experimental data in the literature and is even better than the recommended formula. The overall standard deviations of the proposed formulation from the experimental data in the two references decrease by 85.6% and 78.2% relative to the THTC formulation based on the EN/ISO Standards.

Development of diatomite-based shape-stabilized composite phase change material for use in floor radiant heating

The utilization of phase change materials (PCMs) in floor radiant heating system can reduce energy consumption along with enhancing thermal comfort by reducing indoor temperature fluctuations. However, the leakage and poor thermal performance of PCM limit its further applications. Here, to solve the above problems, sodium acetate trihydrate (SAT)-acetamide (AC)-micron/nano aluminum nitride (AlN) composite phase change material (CPCM) was composited with heat-treated diatomite to prepare diatomite-based shape-stabilized CPCM (SSCPCM) for use in floor radiant heating. The effect of treating temperature on diatomite’s porous structure was analyzed by porosity analyzer to determine the optimal heat-treated diatomite as supporting material. Subsequently, the effects of the mass fraction of diatomite on phase change properties, and shape-stabilized ability of diatomite-based SSCPCM were investigated. Meanwhile, the morphology, chemical compatibility analysis and thermal properties of SSCPCM were discussed in detail. Results indicated that diatomite calcined at 400 °C had large surface area and high porosity, giving it good adsorptive capacity for SAT-AC-AlN CPCM. SSCPCM with 37.5 wt% diatomite had a good shape stability, which melted at 46.5 °C with high latent heat of 162.5 kJ/kg, low supercooling degree of 0.33 °C and good thermal stability and thermal reliability, making it prospective potential in floor radiant heating.

Field measurements and numerical analysis on operating modes of a radiant floor heating aided by a warm air system in a large single-zone church

Space heating can constitute 60–80% of the total energy use of buildings in cold climates. Efficient heating techniques in buildings still rely on operating strategies. In this paper, a church with radiant floor heating in a cold climate is taken as a case of a large single-zone building to analyze the energy use for heating. Field measurements and numerical analysis are both used in the study. Different operating modes of heating, including intermittent heating and constant set-point heating, are compared for energy saving, reliability on indoor climate, and thermal comfort. The intermittent heating by an all-air system with supplied air temperature control results in the highest energy use. The constant set-point air temperature radiant floor heating aided by a warm air system (return air temperature control) is least affected by outdoor temperature with the best reliability and met the thermal comfort requirements throughout the heating season. The main novelty is that an operating mode of cyclic set-point air temperature is proposed. It is found that the small thermal inertia of heating systems should be preferred when the operating mode of cyclic set-point temperature is used to reduce the warm-up period. The results suggest how to operate and reduce the energy use of radiant floor heating systems in a large single-zone building.

Field investigations on operational performance of a novel radiant floor heating equipment applied in a typical office building

Low-temperature radiant heating systems are widely used in buildings with significant energy conservation, and they are convenient for the utilization of low-grade energy resources and household metering. In this study, the practical application of a novel radiant floor heating system (RFHS) in cold regions is investigated via construction of an experimental platform for energy consumption and thermal comfort in an office building in Tianjin, China. The results indicated that the novel radiant floor exhibits higher heating capacity and heat transfer coefficient than that of a traditional radiant floor. During the experiment, the average indoor temperature was 25.0°C in the office room and 22.7°C in the conference room, and all instantaneous indoor temperatures exceeded 21°C. To avoid local thermal discomfort, the supply water temperature of the floor can be appropriately decreased by 2–3°C for operation. Additionally, the power consumption of the system is decreased by approximately 11.4% if the indoor temperature is decreased to 20°C. Hence, a 10-h operation mode per day can be adopted in the office building for energy conservation given that the novel radiant floor exhibits superior initial response to intermittent operation. Practical application: In this study, the practical application effect of a new type of water-passing floor is examined in cold regions to provide a design reference for engineering applications. Therefore, it is expected that the results will be helpful to researchers for indoor environments, heating, ventilating, and air conditioning engineers, system manufacturers, and those who want to analyze the operational performance of a radiant floor heating system.

Preparation and thermal performances of Na2HPO4·12H2O/ SiO2 hydrophilic modified expanded graphite form-stable composite phase change material for radiant floor heating system

Based on Na2HPO4·12H2O as phase change material (PCM) and SiO2 hydrophilic modified expanded graphite (MEG) as supporting carrier and thermal conductivity enhancer, a novel Na2HPO4·12H2O/MEG form-stable composite PCM (CPCM) for radiant floor heating system was fabricated by physical mixing method. The SiO2 mass fraction in MEG and MEG content in CPCM were optimized. The adsorption performance of MEG on Na2HPO4·12H2O and morphology of MEG were systematically discussed. The shape stability, pore structure as well as thermal properties of the obtained CPCM were emphatically investigated. Experimental results showed that MEG containing 15% SiO2 possessed optimal hydrophilicity and adsorption capacity for Na2HPO4·12H2O. With MEG mass fraction of 20%, the CPCM exhibited suitable phase change temperature (33.52 °C), high phase change enthalpy (158.5 J/g), low supercooling degree (2.29 °C) as well as favorable thermal conductivity (1.077 W/m·K), along with the outstanding shape stability and thermal reliability. All these suggest that Na2HPO4·12H2O/MEG CPCM has great application potential in radiant floor heating system.

CFD Analysis of Temperature Distribution of Different Piping Arrangements Used in Radiant Floor Heating System

CFD Analysis of Temperature Distribution of Different Piping Arrangements Used in Radiant Floor Heating System

An experimental investigation on the effect of use of nanofluids in radiant floor heating systems

Hydronic radiant heating systems are widely being run particularly in association with low temperature heat sources. These thermal units are capable of providing high energy saving potential as well as improvement in thermal comfort. Thus, focus on such systems have considerably ascended recently. In this context, augmentation methods have been employed to enhance heat transfer performance of many thermal systems. The use of ultrafine particles in the fluids is considered to be one of the passive techniques, and hence physical properties have been improved compared to the base fluid. Currently, four working fluids’ inlet temperatures are varied from 30 °C to 60 °C, while the mass flow rates are 0.056 and 0.09 kg/s for the heating from floor, and heating from floor along with cooling from walls. Consequently, the examined nanofluids having multi wall carbon nanotube (0.7% vol. cont.) and aluminium oxide (1.26% vol. cont.) have demonstrated better heat transfer performance compared to pure water for similar operating conditions. Nanofluids of greater concentrations such as (0.7% vol. cont.) and (1.26% vol. cont.) have resulted in improvements within the range of 1.7% and 4.9%. Given the improvement in heat transfer acquired, a promising evaluation can be inferred with respect to nanofluids being operated as working fluids in such systems.