Artículos de revista DCIE - ZIES Aldizkari artikuluak

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Open Access
Acoustic and psychoacoustic levels from an internal combustion engine fueled by hydrogen vs. gasoline
(Elsevier, 2022) Arana Burgui, Miguel; San Martín Murugarren, Ricardo; Urroz Unzueta, José Carlos; Diéguez Elizondo, Pedro; Gandía Pascual, Luis; Zientziak; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Ingeniería; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Whereas noise generated by road traffic is an important factor in urban pollution, little attention has been paid to this issue in the field of hydrogen-fueled vehicles. The objective of this study is to analyze the influence of the type of fuel (gasoline or hydrogen) on the sound levels produced by a vehicle with an internal combustion engine. A Volkswagen Polo 1.4 vehicle adapted for its bi-fuel hydrogen-gasoline operation has been used. Tests were carried out with the vehicle when stationary to eliminate rolling and aerodynamic noise. Acoustics and psychoacoustics levels were measured both inside and outside the vehicle. A slight increase in the noise level has only been found outside when using hydrogen as fuel, compared to gasoline. The increase is statistically significant, can be quantified between 1.1 and 1.7 dBA and is mainly due to an intensification of the 500 Hz band. Loudness is also higher outside the vehicle (between 2 and 4 sones) when the fuel is hydrogen. Differences in sharpness and roughness values are lower than the just-noticeable difference (JND) values of the parameters. Higher noise levels produced by hydrogen can be attributed to its higher reactivity compared to gasoline.
Open Access
Assessing the reliability of current simulation of thermoelectric heat pumps for nearly zero energy buildings: expected deviations and general guidelines
(Elsevier, 2019) Martínez Echeverri, Álvaro; Díaz de Garayo, Sergio; Aranguren Garacochea, Patricia; Astrain Ulibarrena, David; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería
This paper makes evident that a rigorous review of simulation methods for thermoelectric heat pumps in nearly-zero energy buildings is needed, as incoherent results during verification and validation of simulation models are reported in the literature. Statistical methods based on uncertainty analysis are deployed to calculate the minimum deviations between experimental and simulated values of the main variables that define the performance of a thermoelectric heat pump, within working scenarios expected in nearly-zero energy buildings. Results indicate that the narrower confidence intervals of these deviations are set by the uncertainties in the calculation of the thermoelecric properties of the thermoelectric modules. The minimum deviation in the prediction of the electric power consumed by the thermoelectric heat pump is ±6% in all scenarios. Likewise, confidence intervals for the heat flow emitted to the hot reservoir range from ±8% for high operating voltages of the thermoelectric heat pump to ±23% for low ones. In similar terms, those of the coefficient of performance range from ±4% to ±21%. These lower limits cannot be reduced unless the uncertainties in the measurement of the thermoelectric properties are reduced. In fact, these confidence intervals are due to increase as more uncertainties are added in the analysis, so wider intervals are expected when heat exchangers and complex heat reservoir are introduced in the system. To avoid so, several guidelines for uncertainty reduction are included in the paper, intended to increase the reliability of the simulation of thermoelectric heat pumps. Among them, relevant is the precise account of the aspect ratio in a thermoelectric module, as well as the deployment of temperature and voltage sensors with systematic standard uncertainties lower than 0.3 °C and 0.01 V respectively. The paper demonstrates the relevance of uncertainty propagation analysis in the verification and validation of the simulation models in this field, and underlines how misleading could be just to compare average values of experimental and simulated results.
Open Access
Complex selective manipulations of thermomagnetic programmable matter
(Springer Nature, 2022) Irisarri Erviti, Josu; Ezcurdia Aguirre, Íñigo Fermín; Sandúa Fernández, Xabier; Galarreta Rodríguez, Itziar; Pérez de Landazábal Berganzo, José Ignacio; Marzo Pérez, Asier; Ciencias; Zientziak; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Institute of Smart Cities - ISC
Programmable matter can change its shape, stiffness or other physical properties upon command. Previous work has shown contactless optically controlled matter or magnetic actuation, but the former is limited in strength and the latter in spatial resolution. Here, we show an unprecedented level of control combining light patterns and magnetic fields. A mixture of thermoplastic and ferromagnetic powder is heated up at specific locations that become malleable and are attracted by magnetic fields. These heated areas solidify on cool down, and the process can be repeated. We show complex control of 3D slabs, 2D sheets, and 1D filaments with applications in tactile displays and object manipulation. Due to the low transition temperature and the possibility of using microwave heating, the compound can be manipulated in air, water, or inside biological tissue having the potential to revolutionize biomedical devices, robotics or display technologies.
Open Access
Diffuse irradiance on tilted planes in urban environments: evaluation of models modified with sky and circumsolar view factors
(Elsevier, 2021) García Ruiz, Ignacio; Blas Corral, María Ángeles de; Hernández Salueña, Begoña; Sáenz Gamasa, Carlos; Torres Escribano, José Luis; Ingeniaritza; Zientziak; Institute of Smart Cities - ISC; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería; Ciencias
Numerous studies have analyzed existing irradiance models for estimating sky diffuse irradiance on tilted planes. However, few have evaluated the suitability of these models for estimating irradiance in obstructed environments, specifically considering the effects of obstacles. In this study, three irradiance models —one of them with five variants— for estimating diffuse irradiance on tilted planes located in urban environments were evaluated. All models have been adapted to consider the effect of an urban canyon on the diffuse irradiance received on a tilted plane through the sky view factor and the circumsolar view factor. All the models were evaluated against the diffuse irradiance values obtained by the ISO 15469:2004(E)/CIE S 011/E:2003 angular distribution model. Therefore, it was necessary to determine the standard sky type corresponding to each record of the measurements performed by a sky scanner at the radiometric station of UPNA (Spain). A total of 4,864 scenarios were considered to occur from the combination of different orientations and inclinations of the plane, and different orientations and aspect ratios of the urban canyon. The results revealed that the Perez model considering a 35° half-angle circumsolar region has the best performance, followed by the Perez model considering a 45° half-angle circumsolar region.
Open Access
Effects of innovative long-term soil and crop management on topsoil properties of a mediterranean soil based on detailed water retention curves
(European Geosciences Union, 2022) Aldaz Lusarreta, Alaitz; Giménez Díaz, Rafael; Campo-Bescós, Miguel; Arregui Odériz, Luis Miguel; Virto Quecedo, Íñigo; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura; Ciencias; Zientziak; Ingeniería; Ingeniaritza; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Gobierno de Navarra / Nafarroako Gobernua
The effectiveness of conservation agriculture (CA) and other soil management strategies implying a reduction of tillage has been shown to be site-dependent (crop, clime and soil), and thus any new soil and crop management should be rigorously evaluated before its implementation. Moreover, farmers are normally reluctant to abandon conventional practices if this means putting their production at risk. This study evaluates an innovative soil and crop management (including no-tillage, cover crops and organic amendments) as an alternative to conventional management for rainfed cereal cropping in a calcareous soil in a semi-arid Mediterranean climatic zone of Navarra (Spain), based on the analysis of soil water retention curves (SWRCs) and soil structure. The study was carried out in a small agricultural area in the municipality of Garínoain (Navarre, Spain) devoted to rainfed cereal cropping. No other agricultural area in the whole region of Navarre exists where soil and crop management as proposed herein is practiced. Climate is temperate Mediterranean, and the dominant soil is Fluventic Haploxerept. Within the study area there is a subarea devoted to the proposed soil and crop management (OPM treatment), while there is another subarea where the soil and crop management is conventional in the zone (CM treatment). OPM includes no-tillage (18 years continuous) after conventional tillage, crop rotation, use of cover crops and occasional application of organic amendments. CM involves continuous conventional tillage (chisel plow), mineral fertilization, no cover crops and a lower diversity of crops in the rotation. Undisturbed soil samples from the topsoil and disturbed samples from the tilled layer were collected for both systems. The undisturbed samples were used to obtain the detailed SWRCs in the low suction range using a HYPROP©device. From the SWRCs, different approaches found in the literature to evaluate soil physical quality were calculated. The pore-size distribution was also estimated from the SWRCs. Disturbed samples were used in the laboratory to assess soil structure by means of an aggregate-size fractionation and to perform complementary analysis from which other indicators related to soil functioning and agricultural sustainability were obtained. The approaches evaluated did not show clear differences between treatments. However, the differences in soil quality between the two forms of management were better observed in the pore size distributions and by the analysis of the size distribution and stability of soil aggregates. There was an overabundance of macropores under CM, while the amount of mesopores (available water) and micropores were similar in both treatments. Likewise, more stable macroaggregates were observed in OPM than in CM, as well as more organic C storage, greater microbial activity, and biomass. The proposed management system is providing good results regarding soil physical quality and contributing also to the enhancement of biodiversity, as well as to the improvement in water-use efficiency. Finally, our findings suggest that the adoption of the proposed practice would not result in a loss in yields compared to conventional management.
Open Access
Gaseous fueling of an adapted commercial automotive spark-ignition engine: simplified thermodynamic modeling and experimental study running on hydrogen, methane, carbon monoxide and their mixtures
(Elsevier, 2023) Urroz Unzueta, José Carlos; Diéguez Elizondo, Pedro; Arzamendi Manterola, Gurutze; Arana Burgui, Miguel; Gandía Pascual, Luis; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Zientziak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In the present work, methane, carbon monoxide, hydrogen and the binary mixtures 20 % CH4–80 % H2, 80 % CH4–20 % H2, 25 % CO–75 % H2 (by volume) were considered as fuels of a naturally aspirated port-fuel injection four-cylinder Volkswagen 1.4 L spark-ignition (SI) engine. The interest in these fuels lies in the fact that they can be obtained from renewable resources such as the fermentation or gasification of residual biomasses as well as the electrolysis of water with electricity of renewable origin in the case of hydrogen. In addition, they can be used upon relatively easy modifications of the engines, including the retrofitting of existing internal combustion engines. It has been found that the engine gives similar performance regardless the gaseous fuel nature if the air–fuel equivalence ratio (λ) is the same. Maximum brake torque and mean effective pressure values within 45–89 N⋅m and 4.0–8.0 bar, respectively, have been obtained at values of λ between 1 and 2 at full load, engine speed of 2000 rpm and optimum spark-advance. In contrast, the nature of the gaseous fuel had great influence upon the range of λ values at which a fuel (either pure or blend) could be used. Methane and methane-rich mixtures with hydrogen or carbon monoxide allowed operating the engine at close to stoichiometric conditions (i.e. 1 < λ < 1.5) yielding the highest brake torque and mean effective pressure values. On the contrary, hydrogen and hydrogen-rich mixtures with methane or carbon monoxide could be employed only in the very fuel-lean region (i.e. 1.5 < λ < 2). The behavior of carbon monoxide was intermediate between that of methane and hydrogen. The present study extends and complements previous works in which the aforementioned fuels were compared only under stoichiometric conditions in air (λ = 1). In addition, a simple zero-dimensional thermodynamic combustion model has been developed that allows describing qualitatively the trends set by the several fuels. Although the model is useful to understand the influence of the fuels properties on the engine performance, its predictive capability is limited by the simplifications made.
Open Access
Giant stress-impedance (GSI) sensor for diameter evaluation incylindrical elements
(Elsevier, 2018-01-01) Beato López, Juan Jesús; Vargas Silva, Gustavo Adolfo; Pérez de Landazábal Berganzo, José Ignacio; Gómez Polo, Cristina; Ingeniería; Ingeniaritza; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Gobierno de Navarra / Nafarroako Gobernua
In this work, a magnetoelastic sensor to detect the micrometer diameter variations of cylindrical elements is analyzed. A nearly zero magnetostrictive amorphous ribbon with nominal composition (Co₀.₉₃Fe₀․₀₇)₇₅Si₁₂․₅B₁₂․₅ was selected as sensor nucleus. The sensor, based on Giant Stress-Impedance (GSI), is attached (glued) along the external perimeter of the cylindrical element. Changes in the cylindrical diameter, DM, induce effective tensile stresses, S, on the ribbon, giving rise to sensitive changes in the high frequency impedance, Z. The sensor response is analyzed in terms of the relationship between the induced strains and the diameter variations, where the effect of geometrical factors (cylinder diameter and sample length) is taken into account. The results indicate that although the maximum GSI ratio depends on the pre-induced bending stresses associated to the cylindrical configuration, the sample length plays the dominant role in the sensor sensitivity. The proposed device enables to monitor the micrometric diameter variation in cylindrical elements, with a maximum strain gauge factor (GF≈-80) for low induced strains.
Open Access
Hydrogen gas-grilling in meat: impact on odor profile and contents of polycyclic aromatic hydrocarbons and volatile organic compounds
(MDPI, 2024) Beriain Apesteguía, María José; Gómez Bastida, Inmaculada; García Murillo, Susana; Urroz Unzueta, José Carlos; Diéguez Elizondo, Pedro; Ibáñez Moya, Francisco C.; Ingeniería; Ingeniaritza; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Ciencias; Zientziak
The effect of fuel (hydrogen vs. butane) on the formation of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) was evaluated for grilled horse meat (very low-fat and low-fat) cooking vertically. Gas chromatography-mass spectrometry was used to analyze PAHs and VOCs. An electronic nose was used to evaluate the odor profile. Total high-molecular-weight PAHs ranged from 19.59 to 28.65 µg/kg with butane and from 1.83 to 1.61 µg/kg with hydrogen. Conversely, total low-molecular-weight PAHs went from 184.41 to 286.03 µg/kg with butane and from 36.88 to 41.63 µg/kg with hydrogen. Aldehydes and alkanes were the predominant family in a total of 59 VOCs. Hydrogen gas-grilling reduced significantly (p < 0.05) the generation of VOCs related to lipid oxidation. The odor profile was not modified significantly despite the change of PAHs and VOCs. The findings indicate that hydrogen is a viable alternative to butane for grilling horse meat. Hydrogen gas-grilling may be regarded as a safe cooking procedure of meat from a PAH contamination point and perhaps sustainable environmentally compared to a conventional technique. The present study provides the basis for the use of hydrogen gas in grilled meat.
Open Access
Impact of a thermoelectric subcooler heat exchanger on a carbon dioxide transcritical refrigeration facility
(Elsevier, 2022) Casi Satrústegui, Álvaro; Aranguren Garacochea, Patricia; Araiz Vega, Miguel; Alegría Cía, Patricia; Astrain Ulibarrena, David; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsita
To improve the performance of vapour compression refrigeration cycles, the inclusion of a thermoelectric subcooler for low-medium power units has been the focus of recent studies due to its robustness, compactness and simplicity of operation. In thermoelectric systems, it has been demonstrated that the heat exchangers used in the hot and cold side of the thermoelectric modules have a critical impact in the performance of the system. This influence has not yet been studied for thermoelectric subcooling systems in vapour compression cycles. This work, for the first time, evaluates the impact that the heat exchangers of a thermoelectric subcooler, included in a transcritical carbon dioxide refrigeration cycle, have, in the performance of the refrigeration cycle. The influence is quantified in terms of: optimum working conditions, coefficient of performance and cooling capacity. The results show that, through an optimization of the heat exchangers of the thermoelectric subcooler, the performance improvements on the coefficient of performance using this technology are boosted from 11.96 to 14.75 % and the upgrade in the cooling capacity of the system rises from 21.4 to 26.3 %. Moreover, the optimum gas-cooler working pressure of the system is reduced and the optimum voltage supplied to the thermoelectric modules increases.
Open Access
Luminance calibration of a full sky HDR imaging system using sky scanner measurements
(Solar Energy Society, 2022) García Ruiz, Ignacio; Sáenz Gamasa, Carlos; Hernández Salueña, Begoña; García Santos, Rafael; Torres Escribano, José Luis; Zientziak; Ingeniaritza; Institute of Smart Cities - ISC; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Ingeniería
A full sky High Dynamic Range imaging system, based on a Single-Lens Reflex camera with a fisheye lens, has been constructed and calibrated with a sky scanner luminance meter. The method considers the geometrical, spectral, timing and orientation issues between instruments. The calibration data sets, having nearly simultaneous measurements under stable sky conditions, were obtained from approximately one month of data using selection variables based in the experimental design. For luminance estimation we use the standard 𝐶𝐼𝐸𝑌 RGB combination and a Spectrally Matched Luminance (𝑆𝑀𝐿) predictor, matching the spectral response of the instruments. With 738 calibration points having luminances up to 23.6 kcd∕m2, covering 98.5% of the sky luminance range, 𝐶𝐼𝐸𝑌 is linearly correlated with sky scanner measurements with a coefficient of determination 𝑅2 = 0.9927 and a Root Mean Squared Error (𝑅𝑀𝑆𝐸) of 7.7%. 𝑆𝑀𝐿 gives better results, with 𝑅2 = 0.9973 and 𝑅𝑀𝑆𝐸 = 5.3%. With 253 calibration points with luminances up to 12.9 kcd∕m2, comprising 94.1% of the sky luminance range, both predictors clearly improve, with 𝑅2 = 0.9964 and 𝑅𝑀𝑆𝐸 = 4.1% in case of 𝐶𝐼𝐸𝑌 and 𝑅2 = 0.9982 and 𝑅𝑀𝑆𝐸 = 2.9% in case of 𝑆𝑀𝐿.
Open Access
Machine learning-based analysis engine to identify critical variables in multi-stage processes: application to the installation of blind fasteners
(DYNA, 2020) Murua Etxeberría, Maialen; Veiga Suárez, Fernando; Ortega Lalmolda, Juan Antonio; Penalva Oscoz, Mariluz; Díez Oliván, Alberto; Ingeniería; Ingeniaritza
Quality control in manufacturing is a recurrent topic as the ultimate goals are to produce high quality products with less cost. Mostly, the problems related to manufacturing processes are addressed focusing on the process itself putting aside other operations that belong to the part’s history. This research work presents a Machine Learning-based analysis engine for nonexpert users which identifies relationships among variables throughout the manufacturing line. The developed tool was used to analyze the installation of blind fasteners in aeronautical structures, with the aim of identifying critical variables for the quality of the installed fastener, throughout the fastening and drilling stages. The results provide evidence that drilling stage affects to the fastening, especially to the formed head’s diameter. Also, the most critical phase in fastening, which is when the plastic deformation occurs, was identified. The results also revealed that the chosen process parameters, thickness of the plate and the faster type influence on the quality of the installed fastener.
Open Access
Mechanical performance of AlCrSiN and AlTiSiN coatings on inconel and steel substrates after thermal treatments
(MDPI, 2022) Liang, Jing; Almandoz Sánchez, Eluxka; Ortiz Membrado, Laia; Rodríguez Lozano, Rafael; Fernández de Ara, Jonathan; García Fuentes, Gonzalo; Llanes, Luis; Jiménez-Piqué, Emilio; Ciencias; Zientziak; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
The objective of this study was to explore the mechanical properties of AlCrSiN and AlTiSiN coatings deposited on Inconel and steel substrates after thermal treatments of 500 °C and 800 °C. Nanoindentation was used to measure the hardness and elastic modulus of the coatings, and microindentation was used for observing the contact damage with Hertzian contact loadings. Microscratch and Mercedes tests were used to evaluate the adhesive strength between coating and substrate with both progressive and static loads, respectively. The surface damage was inspected by optical microscopy and scanning electron microscopy (SEM). Focus ion beams (FIB) were used to mill the cross-sections in order to detect the extent and mode of failure. The results show that AlCrSiN coatings and Inconel substrates exhibit better mechanical performance, even after thermal treatments.
Open Access
Model prediction capacity of ephemeral gully evolution in conservation tillage systems
(Wiley, 2021) Luquin Oroz, Eduardo Adrián; Campo-Bescós, Miguel; Muñoz Carpena, Rafael; Bingner, R.L.; Cruse, Richard M.; Momm, Henrique G.; Wells, R.; Casalí Sarasíbar, Javier; Ingeniaritza; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Ingeniería; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Ephemeral gully (EG) erosion has an important impact on agricultural soil losses and increases field surface hydrology connectivity and transport of pollutants to nearby water bodies. Watershed models including an EG component are scarce and not yet properly evaluated. The objective of this study is to evaluate the capacity of one such tool, AnnAGNPS, to simulate the evolution of two EG formed in a conservation tillage system. The dataset for model testing included runoff measurements and EG morphological characteristics during 3 years. Model evaluation focused on EG evolution of volume, width, and length model outputs, and included calibration and testing phases and a global sensitivity analysis (GSA). While the model did not fully reproduce width and length, the model efficiency to simulate EG volume was satisfactory for both calibration and testing phases, supporting the watershed management objectives of the model. GSA revealed that the most sensitive factors were EG depth, critical shear stress, headcut detachment exponent coefficient b, and headcut detachment leading coefficient a. For EG outputs the model was additive, showing low sensitivity to interactions between the inputs. Prediction of EG spatial evolution on conservation tillage systems requires improved development of gullyerosion components, since many of the processes were developed originally for traditional tillage practices or larger channel systems. Our results identify the need for future research when EG form within conservation tillage systems, in particular to study gully headcut, soil erodibility, and width functions specific to these practices.
Open Access
Monitoring rainfed alfalfa growth in semiarid agrosystems using Sentinel-2 imagery
(MDPI, 2021) Echeverría Obanos, Andrés; Urmeneta, Alejandro; González de Audícana Amenábar, María; González de Andrés, Ester; Zientziak; Ingeniaritza; Institute for Multidisciplinary Research in Applied Biology - IMAB; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Ciencias; Ingeniería; Gobierno de Navarra / Nafarroako Gobernua
The aim of this study was to assess the utility of Sentinel-2 images in the monitoring of the fractional vegetation cover (FVC) of rainfed alfalfa in semiarid areas such as that of Bardenas Reales in Spain. FVC was sampled in situ using 1 m2 surfaces at 172 points inside 18 alfalfa fields from late spring to early summer in 2017 and 2018. Different vegetation indices derived from a series of Sentinel-2 images were calculated and were then correlated with the FVC measurements at the pixel and parcel levels using different types of equations. The results indicate that the normalized difference vegetation index (NDVI) and FVC were highly correlated at the parcel level (R 2 = 0.712), where as the correlation at the pixel level remained moderate across each of the years studied. Based on the findings, another 29 alfalfa plots (28 rainfed; 1 irrigated) were remotely monitored operationally for 3 years (2017–2019), revealing that location and weather conditions were strong determinants of alfalfa growth in Bardenas Reales. The results of this study indicate that Sentinel-2 imagery is a suitable tool for monitoring rainfed alfalfa pastures in semiarid areas, thus increasing the potential success of pasture management.
Open Access
Toward optimal irrigation management at the plot level: evaluation of commercial water potential sensors
(MDPI, 2023) Campo-Bescós, Miguel; Virto Quecedo, Íñigo; Giménez Díaz, Rafael; Aldaz Lusarreta, Alaitz; Ciencias; Zientziak; Ingeniería; Ingeniaritza; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD
Proper irrigation practice consists of applying the optimum amount of water to the soil at the right time. The porous characteristics of the soil determine the capacity of the soil to absorb, infiltrate, and store water. In irrigation, it is not sufficient to only determine the water content of the soil; it is also necessary to determine the availability of water for plants: water potential. In this paper, a comprehensive laboratory evaluation—accuracy and variability—of the world’s leading commercial water potential sensors is carried out. No such comprehensive and exhaustive comparative evaluation of these devices has been carried out to date. Ten pairs of representative commercial sensors from four different families were selected according to their principle of operation (tensiometers, capacitive sensors, heat dissipation sensors, and resistance blocks). The accuracy of the readings (0 kPa–200 kPa) was determined in two soils of contrasting textures. The variability in the recordings—repeatability and reproducibility—was carried out in a homogeneous and inert material (sand) in the same suction range. The response in terms of accuracy and value dispersion of the different sensor families was different according to the suction range considered. In the suction range of agronomic interest (0–100 kPa), the heat dissipation sensor and the capacitive sensors were the most accurate. In both families, registrations could be extended up to 150–200 kPa. The scatter in the readings across the different sensors was due to approximately 80% of the repeatability or intrinsic variability in the sensor unit and 20% of the reproducibility. Some sensors would significantly improve their performance with ad hoc calibrations.

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