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International audience; Intermittency of renewable energy supply causes an issue for grid balancing, as electricity generation is not easily controllable. A method to balance power supply and demand is to store energy during low-demand periods and use it at high demand. Cryogenic energy storage (CES) uses liquefied gas as an energy storage and transfer medium. Recycling cold from the expansion to the liquefier is a way to boost the CES efficiency. As the cold release from the evaporation of cryogen happens at a different time than the gas liquefaction, such an exchange of lowtemperature energy requires a thermal store. A small-scale demonstrator of a packed-bed cold thermal store for use in LAES, integrated with a refrigerated warehouse, was built and run under different thermo-hydraulic conditions. It was able to store 2.92 kWh with round trip efficiency of up to 0.650 when storing for 1 hour and 0.490 when storing for 24 hours.

International audience; Electrical Energy Storage (EES) technologies have received considerable attention over the last decade because of the need to reduce greenhouse gas emission through the integration of renewable energy sources. Renewable sources have an intermittent power output to the electrical grid, thus EES represents a strategic solution in balancing electrical grids and enables the decarbonisation of the energy sector. Cryogenic Energy Storage (CES) is a novel method of EES falling within the thermo-mechanical category. It is based on storing liquid cryogenic fluids after their liquefaction from an initially gaseous state. A particular form of CES, Liquid Air Energy Storage (LAES), has gained growing attention respect to other cryogens. The current state of LAES is still at the development and demonstration stage since no commercial or pre-commercial plants have been built. This technology has been developed in different ways throughout its history (from 1977), and, to the best of our knowledge, no review paper has been published so far about the CES topic. Therefore, the present paper intends to provide a clear picture of the CES/LAES virtues in the literature as well as the challenges associated to the system to be commercially viable. For this purpose, this review includes: an investigation of the properties of cryogens and different CES processes as well as the main ways the system could be combined to other facilities to further enhance the energy efficiency, in particular the combination to a refrigerated warehouse with cold energy recovery from the cryogen evaporation.

International audience

International audience

International audience

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International audience; Two-phase fluids are considered as high-performance fluids for secondary refrigeration thanks to high energy density of phase change material (PCM). Nevertheless, one limitation in such system is thermal energy storage dynamic, in particular PCM charging/discharging rate, which depends generally on fluid temperature and flow rate. In the present work, the influence of pressure on the charging/discharging processes of gas hydrates has been studied experimentally using a stirred tank reactor. A model of stirred tank reactor was also developed and validated. The results showed that pressure can be used to adjust gas-hydrate phase-change temperature and consequently to improve charging/discharging time. For the same working conditions (temperature, flow rate, charging time…), the amount of stored energy using gas hydrates at 3 MPa is two times higher than that using water. The model was used to compare gas hydrates slurries to other slurries at ambient pressure.

International audience

International audience; Secondary refrigeration is an often used solution to reduce the amount of refrigerant leakage and the impact of refrigerants on global warming. The use of two-phase fluids in refrigeration systems is known to increase the quantity of stored energy. In this work, the impact of gas hydrates on the energy release of a heat exchanger is quantified thanks to the dynamic modelling of a secondary refrigeration system. The system is composed of a chiller, a stirred tank reactor (hydrate formation), a loop and a heat exchanger (hydrate dissociation). The model validated by experimental data can be used to simulate various operating conditions in transient and permanent regimes (various slurry mass flow rate, various thermodynamic conditions) and to compare their energy performances. The numerical and experimental results showed better heat exchanger efficiency with hydrate slurry than with water alone.

International audience; Two-phase fluids are considered as high-performance fluids for secondary refrigeration thanks to high energy density of phase change material (PCM). Nevertheless, one limitation in such system is thermal energy storage dynamic, in particular PCM charging/discharging rate, which depends generally on fluid temperature and flow rate. In the present work, the influence of pressure on the charging/discharging processes of gas hydrates has been studied experimentally using a stirred tank reactor. A model of stirred tank reactor was also developed and validated. The results showed that pressure can be used to adjust gas-hydrate phase-change temperature and consequently to improve charging/discharging time. For the same working conditions (temperature, flow rate, charging time…), the amount of stored energy using gas hydrates at 3 MPa is two times higher than that using water. The model was used to compare gas hydrates slurries to other slurries at ambient pressure.

International audience; 50% of the energy consumed in food cold chain is for chilling, freezing and storage steps. For cold storage facilities, refrigeration is the main source of energy consumption with an average of 50 kWh/m3/year. A possible strategy to reduce their energy consumption is to take advantage of the variation of performance of the refrigeration systems during a day due to external and internal temperature variations. Electricity cost can also widely change during a day, depending on the local production. This strategy can be based on additional storage capacities to delay the refrigeration running period, but also on the use of the thermal inertia provided by the storage warehouse itself and the products stored. Using coupled models of the building, products and refrigeration system, potential energy savings of additional thermal storage units in a frozen products warehouse are evaluated.

International audience; Display cabinet is the most widely used equipment to keep food at the required temperature in supermarket. Despite a good design and good control of operating conditions in stores, the heterogeneity of the temperature inside the display cabinet has been observed in several studies. This temperature difference is mainly due to thermal losses through walls, the infiltration of outside air and the heterogeneity of the evaporator temperature. The aim of this work is to develop a transient heat transfer model to study the temperature evolution of loaded products and air inside a display cabinet. The developed model is validated by experimental data obtained with different operating conditions. This model is combined with a model describing the melting and freezing process of a PCM unit located inside the display cabinet. The global model can be used to study the effects of PCM addition on air and food temperatures.

International audience; Two-phase fluids are considered as high-performance fluids for secondary refrigeration thanks to high energy density of phase change material (PCM). Nevertheless, one limitation in such system is thermal energy storage dynamic, in particular PCM charging/discharging rate, which depends generally on fluid temperature and flow rate. In the present work, the influence of pressure on the charging/discharging processes of gas hydrates has been studied experimentally using a stirred tank reactor. A model of stirred tank reactor was also developed and validated. The results showed that pressure can be used to adjust gas-hydrate phase-change temperature and consequently to improve charging/discharging time. For the same working conditions (temperature, flow rate, charging time…), the amount of stored energy using gas hydrates at 3 MPa is two times higher than that using water. The model was used to compare gas hydrates slurries to other slurries at ambient pressure.

International audience; Secondary refrigeration is an often used solution to reduce the amount of refrigerant leakage and the impact of refrigerants on global warming. The use of two-phase fluids in refrigeration systems is known to increase the quantity of stored energy. In this work, the impact of gas hydrates on the energy release of a heat exchanger is quantified thanks to the dynamic modelling of a secondary refrigeration system. The system is composed of a chiller, a stirred tank reactor (hydrate formation), a loop and a heat exchanger (hydrate dissociation). The model validated by experimental data can be used to simulate various operating conditions in transient and permanent regimes (various slurry mass flow rate, various thermodynamic conditions) and to compare their energy performances. The numerical and experimental results showed better heat exchanger efficiency with hydrate slurry than with water alone.

National audience; Cette communication porte sur l'étude expérimentale et numérique de la convection dans la phase liquide de matériaux à changement de phase (MCP) lors de fusion et de la solidification. A partir d'analyses calorimétriques les propriétés thermophysiques liées au changement de phase sont déterminées puis implémentées dans un modèle numérique. Les résultats numériques sont ensuite comparés à ceux obtenus au cours d'essais réalisés grâce à un dispositif expérimental.

International audience; The study presented here aims at finding the ideal method to achieve optimal product quality by using thermal energy storage devices in the case of frozen products storage. These products are usually sensitive to temperature levels and temperature fluctuations. However, reducing storage temperature leads to energy consumption increases. Moreover, temperature peaks are one of the main quality decay causes (e.g. ice crystal growth in frozen food). It is therefore interesting to try to reduce temperature fluctuations. Unsteadystate models were developed to simulate the heat transfer in the refrigeration plant, warehouse, phase change material (PCM), and product. Temperature levels and fluctuations were fed into the product quality model to evaluate its evolution. Results are shown for ice crystal growth in long term ice-cream storage. Various PCM solutions were compared which enabled the optimisation of the on-off control strategy, keeping the same setpoint and adjusting the deadband. In most cases, they helped reduce temperature fluctuations. When PCM was placed in the walls or in the ceiling, the reduction was not very large. The best results were achieved when PCM was put either in an additional heat exchanger placed after the evaporator, in a storage tank (indirect cooling), or in the product packaging. The first solution increases the pressure drop, and thus, the fan pumping power. The second solution also increases energy consumption due to the need of a pump for the secondary refrigerant. The third solution has the advantage of no additional energy consumption and offers an additional protection during transport.

International audience; The addition of a Phase Change Material (PCM) in household refrigerators can reduce significantly the energy consumption of these devices and improve the temperature stability of the products. In this work, we present recent results about the use of PCM units in domestic refrigerators. These results are based on experimental measurements performed according to the standard ISO test procedure and on simulation results. The simulations are carried out using a global model including the thermal energy storage unit, the refrigerator compartment and the refrigerating system. Based on few scenarios with different ambient temperatures, load of products, and various frequencies of opening doors, the impact of the addition of PCM units on the cycling period, the average temperature of the air and the products is given. The thickness of the PCM slab and the melting temperature of the phase change material are also discussed, based on experimental measurements and simulation results.

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International audience; Freezing is an important step in the manufacturing process of ice-cream and sorbet, since the operating conditions have a strong influence on the micro-structure, and consequently on the sensorial attributes of the final product. This steep of freezing is carried out by a scraped surface heat exchanger (SSHE) where the product quality is conditioned by process conditions as the evaporation temperature of a refrigerant fluid, the mix flow rate, the dasher speed and the cylinder pressure due to the air introduction. In order to study the relevance of a control system based on the influence of process variables on product quality, this paper presents a model for a continuous crystallization of a sorbet using the method of moments, which is validated by experimental data. The model created by this methodology has been able to represent the influence of the process conditions during the crystallization of the sorbet on the final product characteristics such as crystal size and the draw temperature in the outlet of the SSHE in absence of air. The model based in moments is studied as a reduced model of the population balance equation and includes the phenomena of heterogeneous nucleation and growth. This model developed represents minimal computational requirements and is highly adapted for optimization and / or process control tasks.

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International audience; A new methodology has been developed to characterize the loss of efficiency of heat exchangers due to a maldistribution of the two-phase flow. The approach consists to measure the distribution of the local heat transfer coefficients with a non-intrusive and fast measurement method, based on a periodic excitation by Joule effect and infrared thermography measurement. An analytical model of the heat transfer is used to deduce heat transfer coefficients from the amplitude of the outside tube temperature fluctuations amplitude and heat flux measurement. This method, initially developed for a cylindrical tube, has been also applied on various tube shapes, including microchannel flat tubes. As an example, the method is used to evaluate the heterogeneity of distribution of an air-water mixture in a compact heat exchanger composed of seven multiport flat tubes. The distribution of heat transfer coefficients was studied for a vertical downward header and horizontal channels and for mass flux from 29 kg.m-2.s-1 to 116 kg.m-2.s-1 and for quality from 0.10 to 0.70. Results are presented and discussed.

International audience; Freezing is an important step in the manufacturing process of ice-cream and sorbet, since the operating conditions have a strong influence on the micro-structure, and consequently on the sensorial attributes of the final product. This paper presents a model for a continuous sorbet crystallization process approach based on the moments model approach and its validation with experimental data. The moments model was used to characterize the influence of the operating conditions during sorbet freezing such as: the evaporation temperature of the refrigerant fluid, the mix flow rate and the dasher rotation speed, on the final product characteristics such as: ice crystal size and draw temperature. The moments model includes heterogeneous nucleation and growth phenomena, has low computational requirements and is quite adapted for optimization or process control tasks.

International audience; In a context of greenhouse gas emissions, oil price rising and intermittent renewable energy sources, energy storage, and more specifically thermal energy storage is one of the best candidates to reduce and optimize the energy use of refrigerating systems. Moreover, the temperature stability and the autonomy of those systems in case of power failure, related to the use of thermal energy storage devices, is also an important factor of food quality and security enhancement. The thermal energy storage (TES) technology has already attracted a number of applications. From short-term storage in food containers to long-term storage in low temperature warehouses, food engineering should also take a full advantage of its potential. Coupled with control strategies as predictive control approach, it can lead to a drastic reduction of energy consumption and a significant product quality enhancement. Through two cases, this paper proposes to show the potential of those technologies for food applications.

International audience; The ice crystal size distribution determines in part the textural properties of sorbet and ice cream. During sorbet and ice cream manufacturing, a narrow ice crystal size distribution with a small mean size is desired, in order to obtain a smooth texture in the final product. This research studied the influence of the mix flow rate, the evaporation temperature of the refrigerant fluid and the dasher speed on the ice crystal size and the draw temperature during sorbet freezing, so as to identify optimal operating conditions. The evolution of the ice crystal size was followed by the focused beam reflectance method (FBRM), which uses an in situ sensor that provides accurate and repeatable information about the chord length distribution (CLD) of ice crystals. Our results showed that the FBRM sensor is a promising tool which makes it possible to monitor online the development of the ice crystals in sorbets containing up to 40% of ice. Decreasing the refrigerant fluid temperature allows us to reduce the ice crystal size and to lower the product's temperature, due to the increase of the supercooling driving force. High dasher speeds slightly decrease the ice crystal chord length, due to the attrition of the bigger ice crystals, which produces new smaller ice nuclei by secondary nucleation. Also, an increase of the dasher speed slightly warms the product, due to the dissipation of frictional energy into the product. Low mix flow rates result in lower draw temperatures because the product remains longer in contact with the freezer wall extracting thus more heat from the product.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]SPEE; International audience; This paper addresses a state of art on the two-phase distribution in the header of compact heat exchangers. The difference of thermophysical properties between liquid and gas involve phase separation and uneven distribution, causing reduction in both thermal and fluid-dynamic performances. The diversity of geometries studied in literature is wide; one of these geometries was selected for a further analysis. In the present paper, the geometry includes cylindrical inlet tube and header and several multiport flat tubes. The major influence of header and channels orientation will be explained, as well as that of channel intrusion depth, flow rate and quality. The two-phase behavior will be discussed to allow an accurate understanding of occurring phenomena.

Le projet présenté dans cette étude s'inscrit dans le cadre du développement de la technologie des minicanaux dans les systèmes de réfrigération. L'utilisation des échangeurs minicanaux en réfrigération permet une forte réduction de la quantité de frigorigène, mais aussi une amélioration globale des échanges thermiques. Utilisés de plus en plus largement pour le condenseur, ils restent cependant très limités en ce qui concerne les évaporateurs.L'objectif principal de ce projet était d'évaluer la performance d'un groupe froid de faible puissance équipé d'un évaporateur à minicanaux. Ce projet comprenait l'étude, la conception et la réalisation de l'évaporateur à minicanaux et s'étendait jusqu'à l'évaluation finale de la performance thermique d'un meuble frigorifique muni de cet évaporateur et sa mise en oeuvre en atmosphère négative, et de quantifier ainsi les difficultés, si elles existent, liées aux phases de givrage et de dégivrage. Cette réalisation expérimentale avait également pour objectif d'obtenir une première évaluation expérimentale des performances d'un évaporateur à minicanaux fonctionnant à température négative. La durée du projet était de 18 mois et a débuté le 14 avril 2009.

National audience; Objectif de l'étude : évaluation des potentialités de l’augmentation de l’inertie thermique d’équipement frigorifiques. Visées : équipements frigorifiques à évaporateurs ventillés de petite à moyenne puissance (quelques kW) à température positive et négative : - Véhicules de transport. - Cellules de refroidissement rapide. - Armoires de conservation.

International audience; Cette étude porte sur la distribution d'écoulements monophasiques dans un échangeur de chaleur à minicanaux. Une section d'essais composée d'un distributeur relié à 8 barrettes de 7 mini-canaux (Dh = 0.889 mm) permet la mesure locale des pertes de pression singulières et régulières dans le distributeur et dans les mini-canaux, ainsi que la distribution des débits dans chaque barrette de mini-canaux. On présente et on analyse les résultats concernant la position verticale du distributeur (écoulement vertical descendant dans le distributeur et horizontal dans les mini-canaux) correspondant à la majorité des applications industrielles. Les résultats expérimentaux sont comparés à ceux obtenus par la simulation numérique ainsi qu'à ceux obtenus à l'aide d'un modèle simplifié unidimensionnel. / This study focuses on the distribution of a single-phase flow in a small channel heat exchanger. A test section consisting of a cylindrical header connected to 8 multiport flat tubes of 7 parallel small channels (Dh = 0.889 mm) enables the measurement of singular and regular local pressure losses all along the header and the small channels, as well as the flow distribution in each small channel tube. The flat tubes are inserted up to the half of the manifold, i-e with an insertion height of 8 mm. We present and analyze the results of a header in vertical position: vertical down flow through the manifold and horizontal flow in the small channels (most of industrial applications). The experimental results are analyzed using a one-dimensional model and compared with those obtained by a numerical simulation.

National audience; L'amélioration des performances énergétiques des systèmes de production de froid est une préoccupation majeure de nos industries du froid. Ce sujet fait l'objet de nombreuses recherches et de nombreux développements. Une grande part des recherches concerne le dimensionnement des composants et leur intégration dans un système complet. En revanche, le nombre de travaux sur une gestion optimisée du système frigorifique, et notamment par le contrôle-commande, reste faible et en particulier sur la commande prédictive intégrant la notion de recherche d'un point de fonctionnement optimal défini par le respect de l'ensemble des contraintes qui pèsent sur le système et/ou sur la chaîne de production.

National audience; Dans les secteurs du froid et du conditionnement d'air, les performances environnementales des systèmes sont fréquemment évaluées grâce à l'indicateur « Total Equivalent Warming Impact » (TEWI, l'effet de réchauffement total équivalent). Seul l'effet de serre est pris en compte à partir de cet indice couramment utilisé qui semble donc inadéquat pour une caractérisation globale, prenant en compte tous les impacts sur l'environnement d'une machine frigorifi que pendant sa durée de vie, c'est-à-dire, de sa mise en fonctionnement à la mise au rebut, « du berceau à la tombe ». Dans cet article, nous proposons d'appliquer l'analyse du cycle de vie (ACV) pour comparer deux systèmes frigorifi ques destinés à une petite application agroalimentaire, avec les mêmes caractéristiques de puissance frigorifi que et utilisant le même frigorigène (R404A). Après un inventaire du cycle de vie des deux systèmes, les résultats de l'analyse montrent que l'utilisation de la technologie à microcanaux et des échangeurs de chaleur compacts dans un tel secteur est meilleure, tant sur le plan énergétique qu'environnemental. L'analyse permet des économies d'énergie, une faible charge en frigorigène, une diminution signifi cative des émissions de CO2 (qui sont divisées par 3), en plus d'une importante baisse des autres impacts environnementaux, en termes de santé humaine (33 %), de qualité de l'écosystème (24 %) et d'épuisement des ressources naturelles (25 %).

International audience; Small-channel heal exchangers are widely used for car airconditioning. However information about theh" behaviour remains scarce. An experime111al device was built to characterize the distribu1ion o. f single and two-phase adiabatic flows in a small channel heal exchanger, and to measure ils singular and regular pressure losses. A transparent polycarbonate test section comprised a 16 mm dia1neter header connected to 8fl at tubes with 7 small channels (D11 = 0.889 mm). Both were studied with horizontal flow and vertical down-flow through the mani f old. The mass flux range was between I 5 and 650 kgl(m2.s) in the manifold and between 100 and 3 000 kgl(m2.�) in the small channels. The range of vapour quality values at the test section inlet was b. etween 0.1and0.9. The two-phase refrigerant was condensed at the outlet of each flat tube in order to measure each flow rate separately.; Les échangeurs de chaleur compacts a mini-canaux sont largement répandus dans la climatisation automobile. Cependant /es informations sur leur comportement demeurent rares. Un dispositif expérimental est réalisé pour caractériser la distribution des écoulements adiabatiques mono-et diphasiques dans un échangeur compact a mini-canaux. Les pertes de pression singulières et régulières sont mesurées. Une section d'essai en polycarbonate transparente comportant un distributeur de 16 millimètres de diamètre relie a 8 barrettes de 7 mini-canaux (D1, = 0.889 mm) est réalisée. Deux configurations sont étudiées : écoulements horizontal et vertical descendant dans le distributeur. La gamme de densité de flux massique varie de 15 a 650 kgl(m2.s) dans le distributeur et de 100 a 3 000 kgl(m2.s) dans les mini-canaux. Les valeurs de titre en vapeur en entrée de section d'essai sont comprises entre 0,1 et 0,9. le réfrigérant diphasique est condense en sortie de chaque barrette a. fin de mesurer chaque débit séparément.

International audience

International audience; Un modèle mathématique a été développé pour simuler l'impact d'un matériau à changement de phase sur le comportement dynamique d'un système frigorifique domestique fonctionnant en tout ou rien. Le changement de phase dans le matériau est décrit par un modèle de conduction pure avec une technique d'immobilisation de l'interface. Dans la modélisation dynamique du système frigorifique, on admet une évolution linéaire du titre en vapeur tout au long des échangeurs et on utilise des propriétés thermophysiques moyennées calculées à partir d'un titre de vapeur moyen. Les résultats du couplage des deux modèles dynamiques montrent clairement l'intérêt de l'intégration d'un élément à chaleur latente dans un réfrigérateur domestique.

National audience; Ce travail expérimental porte sur la distribution d'écoulements adiabatiques mono- et diphasiques dans un échangeur de chaleur à mini-canaux. Une section d'essais composée d’un distributeur relié à 8 barrettes de mini-canaux permet la visualisation des régimes d’écoulement et lamesure locale des pertes de pression régulières et singulières dans le distributeur et dans les mini-canaux. On présente et on analyse les résultats concernant la position verticale du distributeur avec écoulement descendant du frigorigène correspondant à la majorité des applications industrielles.

Un prototype de réfrigérateur à haute inertie thermique utilisant un matériau à changement de phase a été réalisé. Des essais ont été effectués pour plusieurs charges thermiques à différentes températures ambiantes. Les données montrent une nette réduction des fluctuations de température dans l'enceinte réfrigérée et une amélioration du comportement du système en termes d'autonomie et d'efficacité énergétique. L'impact de l'inertie thermique sur le système frigorifique est présenté à partir de ses paramètres de fonctionnement (température d'évaporation et de condensation, consommation du compresseur, autonomie, temps de fonctionnement).

[Departement_IRSTEA]EA [TR1_IRSTEA]TEPSA / ENERFRI; Small-channel heat exchangers are widely used for car air-conditioning. However information about their behaviour remains scarce. Thus an experimental device was built to characterize the distribution of a two-phase flow in a small-channel heat exchanger and to measure the singular and regular pressure losses. Both were studied with horizontal flow and vertical down-flow through the header. A transparent polycarbonate test section comprised a 16 mm diameter header connected to 8 multi-port flat tubes (Dh = 0.889 mm). The mass flux range was between 15 and 650 kg/(m².s) in the manifold and between 100 and 3 000 kg/(m².s) in the small channels. The range of vapour quality values at the test section inlet was between 0.1 and 0.9. The two-phase refrigerant was condensed at the outlet of each flat tube in order to measure each flow rate separately. The refrigerant distribution was studied in single and two-phase flows, the pressures losses were measured.

In refrigerating and air conditioning fields, the environmental performances of systems are frequently evaluated by using the TEWI indicator (Total Equivalent Warming Impact). Alone the greenhouse effect is taken into account from this widespread index which seems nevertheless to be inadequate for a global characterisation, including whole environmental impacts of a refrigerating machine during its life, i.e. from cradle to grave. In this article, we propose to apply the Life Cycle Analysis (LCA) approach to compare two refrigerating units, destined to an agro-food small application, having the same characteristics of refrigerating capacity and use the same refrigerant (R404A). After a detailed life cycle inventory of both systems, the analysis results show that the use of the micro-channel technology and compact heat exchangers in such sector is energetically and environmentally friendly. It provides an energy saving, a low refrigerant charge, a significant CO2 emissions reduction (division by 3), in addition of an important decrease of other environmental impacts in terms of human health (33%), ecosystem quality (24%) and resources depletion (25%).

A prototype refrigerating system was developed; it uses the small-channel technology for the condenser and a compact evaporator so that the refrigerant quantity was reduced drastically. The objective of this study was to demonstrate that it is possible to reduce until to 90% the refrigerant charge of low capacity refrigeration units (less than 15 kW refrigeration capacities) with HFC refrigerant, by using compact heat exchangers, low capacity liquid receivers and small diameter pipes. Experimental measurements were performed and compared to measurements on a same capacity refrigerating system using traditional diameters for the evaporator, condenser, pipes... The mass reduction is mainly due to a 90% reduction of internal volume between the two systems. The performance of both systems and their impact on the environment using the TEWI criteria were compared. The results tend to prove the potential of the application of the small-channel technology compared to the traditional technology: 10% COP enhancement due to the enhancement of the internal heat transfer coefficients, 66% TEWI reduction.