Primary Refrigerant Research Articles

Experimental Investigation of R404A Indirect Refrigeration System Applied Internal Heat Exchanger: Part 1—Coefficient of Performance Characteristics

In this study, the performance characteristics of an R404A indirect refrigeration system (IRS) applied to an internal heat exchanger (IHX) is evaluated for supermarkets and hypermarkets. In a direct expansion system, R404A is the primary refrigerant and R744, a brine, is the secondary fluid. While there are abundant studies analyzing the theoretical performance of IRS, experimental research on IRS is lacking, and there are no papers that address the results of changes in the IHX in detail. In this study, the results achieved by modifying various parameters are experimentally evaluated to provide fundamental data for designing the optimal IRS. In the main results, looking at the trend of the increase in IHX efficiency, the change is very minimal when the efficiency is above 50%, so it is ideal to apply an IHX efficiency of about 50% considering economics and COP, etc. Applying the results in this study enables the operation and maintenance of IRSs as an eco-friendly system by achieving energy efficiency through optimizing the system coefficient of performance and securing economic feasibility by minimizing the R404A charging amount of the refrigeration cycle. To serve supermarkets and hypermarkets, R744 as a secondary fluid may help to realize an ecologically friendly, compact IRS system with a high heat transfer coefficient that can operate at low temperatures (−35 to 5 °C).

Energy, exergy, economic, and environmental compromising performance of dual-stage evaporation-ammonia hybrid compression–absorption refrigeration system for the cooling supply of keto-benzene dewaxing process

Absorption refrigeration systems driven by low-temperature waste heat is one way to achieve “carbon neutrality”. Meanwhile, the keto-benzene dewaxing equipment needs cooling capacity of 5 MW which refrigeration temperature of –10 °C and –25 °C. This paper researches the feasibility of DSE-AHCARS (Dual-stage Evaporation-Ammonia Hybrid Compression-Absorption Refrigeration System) replacing the vapor compression refrigeration system for keto-benzene dewaxing process based on 4E (Energy, Exergy, Economic, and Environmental) analysis. At the primary and secondary stage evaporation temperature of 0 and –23 °C, COP reaches the maximum value of 0.85. However, COP-Electricity reaches the minimum value of 8.1. When the secondary stage refrigeration temperature is –23 °C, CO2 emission increases from 1150 t·a–1 to 3600 t·a–1, and Life Cycle Climate Performance increases from 3.29×104 tons to 7.7×104 tons with the primary stage refrigeration temperature is –15 °C to 0 °C. As well as matching three parameters to ensure the 4E compromising performance by the multi-objective optimization. To guarantee the Life Cycle Climate Performance is less than 5.5×104 tons, the payback period is less than 2 yr, and COP is greater than 0.6 at the optimal operation ranges that refrigeration temperature difference between primary stage and secondary stage is within 20 °C. The power of DSE-AHCARS was reduced by 77% compared with the vapor compression refrigeration system. Therefore, the DSE-AHCARS can reduce CO2 emissions by about 6250 t·a–1 and save 1.2×105 tons of CO2 in the Life Cycle Climate Performance term. This result shows that the DSE-AHCARS can completely replace the vapor compression refrigeration system.

Numerical investigation in effects of refrigerants’ thermodynamic properties on performance of supersonic ejector

ABSTRACT Using zeotropic mixtures with unique temperature glide characteristics as the working medium in heat-driven ejector refrigeration system will potentially reduce the irreversible losses in heat exchange process. However, the intrinsic link between the pure/mixture refrigerants’ thermophysical properties and the entrainment performance of supersonic ejector has not yet been elucidated. In this study, a novel ejector CFD model is established by coupling the real-gas thermodynamic equation and species transport equation, then the relationships between thermophysical properties of pure/mixture refrigerants and ejector’s dimensionless operational parameters were thoroughly investigated. The results indicated that the ejector expansion ratio rises as primary flow inlet temperature or refrigerant’s normal boiling point increases, while the dimensionless parameters of primary nozzle are relatively insensitive to the variation of primary flow inlet temperature and refrigerant’s boiling point, resulted in changes of supersonic jet expansion behaviour. Moreover, the specific volume and adiabatic index change characteristics resulted in minor fluctuations of primary nozzle’s dimensionless parameters. When the bubble point temperature is fixed at 30℃ in the condenser, the saturated vapor/liquid phase pressure glide characteristics of R600a/R1234ze mixture may lead to an increasement of ejector’s compression ratio.

State-of-the-art of cold energy storage, release and transport using CO2 double hydrate slurry

CO2 hydrate slurry is a promising cold storage and transport medium due to the large latent heat, favorable fluidity and environmental friendliness, and the CO2 utilization can also be simultaneously achieved. However, the phase change pressure of CO2 hydrate is too high for applications in refrigeration system, thus the thermodynamic promoters are used to moderate the phase change conditions by forming CO2 double hydrate. In this review, a comprehensive summarization of research progresses of CO2 double hydrate is presented, encompassing the aspects of thermodynamic and kinetic characteristics, cold storage and release, cold transport and system operation. Quaternary salts, tetrahydrofuran, and cyclopentane are concluded to be the main thermodynamic promoters used to alleviate hydrate formation conditions. The cold storage capacity of CO2 double hydrate slurry highly depends on CO2 absorptivity which can be enhanced by increasing pressure, adding kinetic promoters and external disturbance. The non-Newtonian behaviors of most CO2 double hydrate slurries exhibit shear-thinning characteristics and addition of anti-agglomerates can effectively reduce their apparent viscosity. There is an optimal hydrate mass fraction and phase change temperature that make the system energy efficiency the highest due to the reduced pumping power consumption and improved primary refrigeration system efficiency. On the way to practical applications, the research challenges remain in elucidation of underlying mechanism of CO2 absorption and release with the presence of kinetic promoters, stable control of cold storage and release processes, and the detailed heat and mass transfer characteristics. In addition, operation strategy, optimization techniques, economic analysis and CO2 management method of the entire system are potential research topics.

Experimental analysis of vapour compression refrigeration system using nano lubricant with refrigerant R-134a

It has been proved that due to addition of nanoparticals to the refrigerant results in improvement in thermophysical properties and heat transfer characteristics of the primary refrigerant, which improves the coefficient of performance of the refrigeration system. In this experimental analysis of vapour compression system, the performance study has been carried out by preparing the nanolubricant. In this experimental study, three cases are considered. The compressor of the system filled with pure polyolester oil, SUNISO-3GS oil and polyolester oil + titanium dioxide nanoparticles as lubricant. In the nanolubricant, the volume concentration of the nanoparticles is 0.2 %. The experimental study shows that vapour compression refrigeration system works smoothly with nanorefrigerant. In this experimental study, it has observed that when nanolubricant used in place of traditional Polyol ester oil, the refrigerating effect has been increased and the compressor power consumption has reduced by 27% and the refrigeration system coefficient of performance improves by 29%. The analysis shows that the enhancement factor in the evaporator is 1.2 when nanorefrigerants are used instead of pure refrigerant. The properties of refrigerant like thermal conductivity and density are also studied for the nanolubricant by using the Labview software, in which the thermal conductivity & the density of R134a and nanolubricant mixture are observed higher in comparison with the R134a and pure lubricant mixture.

Thermodynamic, Exergetic and Thermoeconomic Analyses of Double-Effect LiBr–Water Absorption Refrigeration Systems with a 5 kW High Temperature PEMFC as Heat Source for Data Center Applications

Thermodynamic, exergetic and thermoeconomic analyses were performed on two types of double-effect LiBr–water absorption refrigeration systems (ARS) for use with a 5-kW high-temperature proton exchange membrane fuel cell (HT-PEMFC) as a heat source. Proper temperatures of the high-pressure generator, combined generator and condenser, condenser, absorber and evaporator were determined to meet the requirements of constant cooling demands for data center operations. The heat balance of the combined unit of generator and condenser in the industrial double-effect LiBr-water ARS is important for determining the flow rate of the primary vapor refrigerant from the high-pressure generator. The industrial double-effect ARS system, whose analysis has not been studied analytically, outperformed the series double-effect system and provided 6.5 kW of cooling capacity with a coefficient of performance of 0.99. The unit cost of chilled water estimated by the modified productive structure analysis (MOPSA) method is approximately 7.18 USD/GJ (=0.026 US$/kWh). Effective exergetic efficiency of HT-PEMFC with the industrial ARS increases to 57.6% from 47.0%.

Thermodynamic analysis and economic assessment of a carbon dioxide hydrate-based vapor compression refrigeration system using load shifting controls in summer

The present work proposed a novel two-stage carbon dioxide hydrate-based vapor-compression refrigeration system. The proposed system applied pure carbon dioxide hydrate as the primary refrigerant and arranged both of hydrate formation and dissociation at the low-pressure stage. The thermodynamic and economic models were developed and then performances of the proposed system using load-levelling storage and full storage operations were evaluated and compared with those of a conventional carbon dioxide single-stage vapor-compression refrigeration system, which is treated as the baseline and with no energy storage. The simulation results indicate that the design capacity of the proposed system using full storage is the largest among the three systems, but with lowest operation cost, and with the incentivization of electricity prices ratio of on and off-peak this cost savings would raise significantly. Noted that the bill structure reveals the load-levelling storage system saves most on the water consumption. Due to the dominant expenditure on the two compressors, compare with the baseline system, the initial capital cost of the full storage system was 75.5% higher, whereas that of the levelling-load storage system was only 21.5% higher. Finally, this paper discussed the economic feasibility on the initial capital cost for the proposed system and developed an indication map to predict the profit years in case of that the new system using load-levelling storage operation replaces the baseline system assuming a system lifetime of 15 years under different electricity prices ratios.

An Ultra-Low Temperature Transcritical R744 Refrigeration System for Future Detectors at CERN LHC

The cooling systems of the future tracking detectors of the ATLAS and CMS experiments at the Large Hadron Collider (LHC) at CERN will be entirely based on CO2 refrigeration technology. The system is a booster refrigeration system, composed of a two stage primary part with transcritical R744 equipment and a low temperature secondary CO2 pumped loop. The primary refrigeration sub-system installed on surface provides cold R744 at −53∘C to the CO2 pumped loops installed 100 m underground and rejects the heat exchanged. The process must be reliable and remain stable regardless of the amount of heat exchanged, which will amount to hundreds of kilowatts and is expected to vary throughout the lifetime of the detectors. The paper discusses the concept adopted for the innovative transcritical R744 cycle and describes the technical details of the first prototype built.

Cooling System Performance Comparison of Refrigerant R-134a and MC-134 on Ice Slush Machine

Ice Slush Machine uses a direct cooling vapor compression system. The primary refrigerant used in such a system mostly is hydrofluorocarbons (HFCs), such as R134a. R134a is a retrofit for refrigerant R-12 which is included in the chlorofluorocarbon (CFC) type of refrigerant. CFC-type refrigerants have a dangerous impact on the environment. Hydrocarbon refrigerant MC-134 is an alternative for R-134a because it has a low potential value for environmental damage. The secondary refrigerant used was propylene glycol and the product used was 3.5 liters of Coca-Cola. From the test results when the system using R134a had an average COP actua l and an average COP carnot of 2.6 and 4.55, respectively, and the energy consumption was 1.571 kWh with an average efficiency of 57%, while in a system with MC-hydrocarbon refrigerant 134 obtained an average COP actual and an average COP carnot of 2.8 and 4.5, respectively and the energy consumption of 1.325 kWh with an average efficiency of 62%. Therefore, MC-134a had COP actual greater than R-134 and electrical energy consumption of MC-134 was less than R-134a.

Modelling and thermodynamic analysis of ejector flow for application at design and off design operating conditions in an ejector air conditioner

Ejector flow in an ejector air conditioning system using R245fa is analysed for entrainment ratio and potential refrigeration effect, at varying temperature and heat input conditions in the generator ranging from 60C to 100C and 2kW to 5kW respectively. The effect of varying generator temperature in cooling capacity of the system when the vapour ejectoris operating at design evaporator and condenser temperatures of 10C and 35C respectively is investigated. The mathematical model of the vapour ejector with optimum area ratio is developed and validated. A critical entrainment ratio of 0.385 is obtained corresponding to generator temperature of 100C. When the generator temperature is varied from 60C to 100C, the cooling capacity range from 0.3kW at generator heat input of 2 kW to 1.78 kW at 5 kW heat input. Further, the operation of the system is analysed for off design operating condition corresponding to reduced heat input rate in the generator. In that case the state of primary refrigerant flow in ejector inlet will be two phase and a mathematical model for two-phase ejector flow is developed and validated. Ejector flow analysis revealed the minimum quality of flow at ejector inlet to maintain adequate backpressure for condensation to occur range from 0.72 at 60C to 0.22 at 100C. The corresponding refrigeration refrigeration effect produced is less than the respective designed operation value byits 12.2% to 8%. Further, analysis of the system shows that at least 7 kW heat input at 100C is required to produce 1 ton of cooling effect.
 Ejector flow in an ejector air conditioning system using R245fa is analysed for entrainment ratio and potential refrigeration effect, at varying temperature and heat input conditions in the generator ranging from 60C to 100C and 2kW to 5kW respectively. The effect of varying generator temperature in cooling capacity of the system when the vapour ejectoris operating at design evaporator and condenser temperatures of 10C and 35C respectively is investigated. The mathematical model of the vapour ejector with optimum area ratio is developed and validated. A critical entrainment ratio of 0.385 is obtained corresponding to generator temperature of 100C. When the generator temperature is varied from 60C to 100C, the cooling capacity range from 0.3kW at generator heat input of 2 kW to 1.78 kW at 5 kW heat input. Further, the operation of the system is analysed for off design operating condition corresponding to reduced heat input rate in the generator. In that case the state of primary refrigerant flow in ejector inlet will be two phase and a mathematical model for two-phase ejector flow is developed and validated. Ejector flow analysis revealed the minimum quality of flow at ejector inlet to maintain adequate backpressure for condensation to occur range from 0.72 at 60C to 0.22 at 100C. The corresponding refrigeration refrigeration effect produced is less than the respective designed operation value byits 12.2% to 8%. Further, analysis of the system shows that at least 7 kW heat input at 100C is required to produce 1 ton of cooling effect.

Universal heat exchanger for air and evaporative cooling of electronics

We present a heat exchanger design that was developed for low temperature cooling of medium power density electronics and, more specifically, for the particle detectors of the “forward” AFP and TOTEM experiments at the CERN Large Hadron Collider (LHC). The heat exchanger uses a metal foam to enhance internal heat transfer, it is galvanically insulated from the pipes of the cooling system and hermetically sealed. The notable advantage of this heat exchanger is that the same design can be used with air or evaporating refrigerant as the cooling fluid. This can be beneficial when the development and testing phases of the detectors take place in laboratories with limited cooling equipment, or for backup cooling solutions that move from a primary refrigerant system to air-cooling. Several prototypes have been built and tested, both in the laboratory and in direct application in the AFP experiment at the LHC. The temperature difference between the inlet air and the surface of the heat exchanger is 20 °C with a 20 W heat load, this difference drops to 10 °C when R-218 refrigerant is used instead of the air.

KAJI EKSPERIMENTAL SISTEM DESTILASI ASAP PEMBAKARAN SAMPAH PLASTIK MENJADI BAHAN BAKAR ALTERNATIF DENGAN PENDINGINAN SISTEM REFRIGERASI KOMPRESI UAP

One step to reduce plastic waste and at the same time to produce alternative fuel is by pyrolysis of smoke destilation of plastic waste burning result because basically the material of plastic waste is hydrocarbon. This research will be discussed about experimaental study of smoke destilator machine of plastic waste burning result using vapor compression refrigeration system in various temperature without analizing the economical factor. There was two step destilation done, using local temperature air and by refrigerated heat exchanger using 35% propylene glycol as secondary refrigerant and with R134A as the primary refrigerant. In destilation step using secondary refrigerant was done by baffled counter flow tube in tube heat exchanger in order to obtain turbulent flow and was done in various temperature that was local temperature air and temperature under 10℃: 9℃, 3℃ and -3℃. The plastic waste which was burnt is 2 kg Low Density PolyEthylene LDPE using reactor with L:40cm x W:40cm x H:60cm and 3 kg elpiji gas burner in temperature of ±400°C. The design was assumed to maximize plastic waste burnt result smoke destilation process. The lower destilation temperature generate the higher alternative fuel volume. During ±4 hours measurement, with temperature of 9℃ generates 480 mL fuel, while 3℃ generates 615 mL fuel, -3℃ generates 710 mL fuel and with local temperature destilation only generates 390 mL fuel.

Miniaturized Traveling-Wave Thermoacoustic Refrigerator Driven by Loudspeaker: Numerical Design

Ordinary refrigeration systems such as vapor-compression refrigerators are the commonly used devices in industry, mostly for their high efficiencies. However, they make a significant contribution to the depletion of Ozone and global warming due to their operational refrigerants. Hence, thermoacoustic refrigeration can be a great alternative candidate which uses inert gases such as air, helium and nitrogen as the primary refrigerant. Thermoacoustic refrigerators convert the acoustic power (sound waves) into a thermal effect (cooling power). Thermoacoustics can be counted as a new technology that has a strong potential toward the development of the thermal applications. This study aims to design and fabricate miniaturized traveling wave thermoacoustic refrigerator which can be driven by an ordinary loudspeaker. The optimized numerical design of the refrigerator shows an overall efficiency (cooling power over input electricity) of nearly 66% at a temperature difference of 25[Formula: see text]K (between cold and ambient heat exchangers). The maximum estimated cooling power is 65[Formula: see text]W at coefficient of performance (COP) of 2.65.

Experimental studies of vapour compression refrigeration system with eco-Friendly primary refrigerant and brine mixed with nano particles as secondary refrigerant

This paper is to study the thermal analysis of vapor compression refrigeration system using R134a in primary circuit and Al2O3-Water based nano-fluids in secondary circuit. The study provides the information of the secondary fluids input conditions, Performance parameters of vapour compression refrigeration system using eco-friendly refrigerants and without nano materials, Effect of overall evaporator heat transfer coefficient using different nano particles mixed with R718 in the secondary evaporator circuit and R134a in primary circuit, the compressor power consumption and the system overall energy performance. Such an analysis with the help of engineering equation solver software (EES) tool can be conveniently useful to compare the thermal performance of different nano-particles (i.e., Al2O3, TiO2) based nano fluid as a secondary fluid in a vapor compression refrigeration system.

Water flow boiling heat transfer in vertical minichannel

In recent years, microchannel water flow boiling has demonstrated excellent heat removal capabilities, particular for nuclear reactor safety utilities, ranging from mini-scale cooling devices to chemical industry plant purposes. Of particular interest is cooling technology using water as the primary refrigerant. This paper presents the results of an experimental investigation into the water boiling heat transfer in a minichannel conduit vertically oriented with the upward flow. The test section was a circular minichannel tube made of stainless steel with a 2.12 mm inner diameter. To observe the flow regime, the test section was equipped with sight tubes made of transparent perfluoroalkoxy alkane resin and Pyrex glass at the inlet and outlet, respectively. Water flow boiling experiments were conducted at a saturation temperature of approximately 100 °C, with the mass flux of water as the working fluid from 20 to 120 kg/m2·s, and the average vapor quality in the test section inlet of approximately 0.05 to 0.9. The predicted two-phase flow regimes at the test section were classified as three patterns, namely slug, annular, and churn flows, using a flow pattern map with the vapor quality as the abscissa versus the mass velocity as the ordinate. The flow patterns were confirmed and visualized by observations at the test section outlet sight tube. The characteristics of the heat transfer and fluid flow were analyzed. Moreover, the forced convective heat transfer coefficient and pressure drop in the test section were determined based on the experimental data. The highest mass flux yielded the highest convective heat transfer coefficient. Despite this significant heat transfer coefficient improvement, the pressure loss was higher than that for a higher mass flux, indicating that the pressure loss was more pronounced owing to the presence of the minichannel at a higher mass flux.

Influence of circulating pump efficiency on the heat exchange process in a plate heat exchanger used in a solar heating installation

In solar heating systems with an absorber area of more than 20 m2, a plate heat exchanger is used as a separator between the primary glycol-based refrigerant and secondary water. The use of a plate heat exchanger enables an increase in the heat exchange area compared to the standard coil heat exchangers located inside the domestic hot water tank. An important problem is to determine the volume flow rate on both the primary and secondary side of the exchanger. The paper presents an analysis of the influence of the circulation pump efficiency on the primary and secondary side of the heat exchanger installed in a solar heating installation on the intensity of the heat exchange process.

Efficiency and Sustainability Improvement of Vapor Compression Configurations and a H2O/LiBr Absorption System Through Thermodynamic Analysis and Parameter Variation

The need for more efficient and sustainable refrigeration systems has promoted the development of new configurations. Subcooling have shown to improve the coefficient of performance whereas thermal energy driven configurations allow renewable sources to be employed. In this study thermodynamic models have been developed for simple, suction line heat exchanger, integrated and dedicated subcooling vapor compression systems using R-134a as the primary refrigerant and for a single-stage absorption refrigeration system with H2O/LiBr. The variation exhibited by the performance of the refrigeration systems is examined at various operating conditions finding that COP increases as condenser temperature decreases and evaporator temperature increases; high COP values are obtained with increasing generator temperature and LiBr concentration in the case of the absorption system. Low and zero emissions associated to subcooling strategies and absorption systems, due to the higher efficiencies and renewable character of the energy source respectively, were obtained when comparing the environmental impact.

Performance analysis of vapour compression water chiller with magnetic flux at the condenser exit

The refrigeration and air-conditioning system contribute significantly to building energy consumption. Therefore, it is necessary to develop new technologies that can achieve a higher coefficient of performance (COP). Employing a magnetic field (MF) on the condenser tube (between the condenser outlet and the capillary tube) is a new technique that helps in improving efficiency and cooling capacity of air-cooled vapour compression cycle (VCC) water chiller. In this work, four pairs of the permanent magnet of 3000G field strength were installed on the condenser tube (between exit of the condenser and inlet of the capillary tube) of the VCC water chiller test setup. The performance of the test setup was compared by applying and removing an MF from the condenser tube to estimate an enhancement in the VCC water chiller system with an MF. Experiments were carried out using R404A as a primary refrigerant in the VCC system. This work discusses the outcomes of magnetic flux applied to the condenser tube at various locations of VCC on COP and power consumption of the water chiller unit. The percentage growth in refrigeration effect ranged between 0.58 and 8.82, and a higher value of the refrigeration effect of 8.82 was found by using the first magnet pair. Experimental outcomes show that compressor power consumption decreased by 4.43% with an increase in the number of magnet pairs from 1 to 4. The VCC system performance was improved by 8.94%.

EXPERIMENTAL ANALYSIS OF HEAT-PUMP INTEGRATED WITH SOLAR ENERGY

The objective of the present work is to analyze the performance of an equipment used in water heating for domestic and commercial use. The hot water is obtained by conventional vapor compression heat pump machine, using the R-134a as primary fluid refrigerant. This way, the plate evaporator is in contact with the hot source originated from incandescent lamp, simulating the solar energy and the condenser is in contact with the cold source represented by the water storage. A radiator is used to collect the hot water that comes from the hot water storage. The parameters analysed in the research are the energy dissipated by the radiator, the COP of systems and the variation of the water flow rate.

Número mais provável miniaturizado e microbiologia convencional para isolamento de Salmonella spp. em abatedouros de frangos de corte

Os produtos de origem avícola podem ser importantes veículos de transmissão de Salmonella spp. para humanos e, dentre os vários parâmetros que determinam a qualidade de um alimento, destacam-se os que definem suas características microbiológicas. Objetivou-se detectar e quantificar Salmonella spp. na tecnologia de abate de frangos de corte por microbiologia convencional (MC) e número mais provável miniaturizado (mNMP). As coletas foram realizadas em duas visitas a três abatedouros sob Inspeção Federal e em seis pontos de coleta em triplicata, definidos como: recepção das aves (swabs de cloaca e esponjas de gaiolas de transporte antes e após a higienização) e carcaças (após pré resfriamento em chiller, após o gotejamento e antes da embalagem primária e congeladas a -12oC por 24 horas), totalizando 108 amostras. Identificou-se Salmonella spp. em três dos seis pontos do fluxograma de abate e em dois dos três estabelecimentos amostrados, independentemente do método utilizado, perfazendo 5,5% de positividade, onde destaca-se a contaminação nas gaiolas de transporte das aves após a higienização. Não foi possível correlacionar os resultados da microbiologia convencional e do mNMP ou mesmo quantificar a contaminação ao longo da tecnologia de abate, o que indica a necessidade de se utilizar um método qualitativo aliado ao método de quantificação quando Salmonella estiver presente em quantidades inferiores ao limite de detecção do mNMP proposto (0,13 NMP/mL). Os sorovares identificados foram Typhimurium, Panama, Lexington e Rissen, consideradas paratíficos e, portanto, potencialmente capazes de causar infecções em humanos, embora estes sorovares não tenham sido isolados em produtos finais e sim na chegada dos frangos aos abatedouros (swabs de cloaca e gaiolas de transporte). A identificação de Salmonella spp. nas gaiolas de transporte após a higienização é um indicativo da necessidade de revisão e adequação dos métodos automatizados de lavagem atualmente utilizados nos abatedouros.