Auswahl der wissenschaftlichen Literatur zum Thema „Gasoline vapor control“

In practice, the volatile organic compounds (VOCs) pollution can exist when refueling due to the properties of the gasoline, low viscosity and high saturated-vapor pressure. A new gasoline vapor recovery system involving frequency conversion technology and machine learning is developed to cope with this problem. In the proposed system, firstly, the pumping capacity of the vacuum pump is evaluated, and test shows an almost linear relationship between suction volume and frequency. Then, the Multi-Layer Perception (MLP) neural network and the support vector regression (SVR) are employed to predict the gas-liquid ratio, and the numerical examples are presented to prove the high prediction accuracy of the MLP and SVR, respectively, where the MLP neural network has better generalization ability. Finally, compared with the two gasoline vapor recovery systems based on the 1: 1 fixed control model and the PID control model, respectively, the gasoline vapor recovery efficiency is improved significantly by the new gasoline vapor recovery system.

In practice, the volatile organic compounds (VOCs) pollution can exist when refueling due to the properties of the gasoline, low viscosity and high saturated-vapor pressure. A new gasoline vapor recovery system involving frequency conversion technology and machine learning is developed to cope with this problem. In the proposed system, firstly, the pumping capacity of the vacuum pump is evaluated, and test shows an almost linear relationship between suction volume and frequency. Then, the Multi-Layer Perception (MLP) neural network and the support vector regression (SVR) are employed to predict the gas-liquid ratio, and the numerical examples are presented to prove the high prediction accuracy of the MLP and SVR, respectively, where the MLP neural network has better generalization ability. Finally, compared with the two gasoline vapor recovery systems based on the 1: 1 fixed control model and the PID control model, respectively, the gasoline vapor recovery efficiency is improved significantly by the new gasoline vapor recovery system.

Tightness, dynamic back pressure and air to liquid volume ratio (A/L) of vapor recovery system of gasoline filling stations were detected, VOCs was analyzed by GC, in-station diagnostic operation status was inspected by site investigation. The results denoted that the modification of gasoline filling stations was not complete and the installed vapor recovery systems didn’t operate under normal state. Insufficient understanding on vapor recovery control, poor management and unsuitable regulations resulted in these problems. Some solutions such as enhancing the propaganda, making preferential policies, holding training for the connected staffs, maintenance in time, and revising the unsuitable regulations were proposed. This study has positive significance in promoting vapor recovery control developed in China.

This paper studied gasoline vapor combustion catalyzed by Pd/Al2O3 in oxygen-poor condition. By adjusting the gasoline vapor and oxygen, the inlet temperature and flow rate, collecting data of temperature difference between outlet and inlet as well as the change of gas mixture, the study analyzed the various factors in the catalytic combustion process, and optimized the process control parameters. The results indicated that catalytic combustion was more efficient at the ignition temperature of 274 °C, burned 50% of gasoline vapor in oxygen-poor condition (O2 fraction was 12%).

Many state and local air pollution control agencies are considering rules that would require recovery of vapors from marine loading operations to help meet EPA-mandated ozone level regulations. Most of the proposed rules will require recovery of vapors from crude oil and gasoline loadings. Several marine vapor recovery systems designed for dedicated ships in a dedicated trade have been operated successfully over the past few years, but a universal system has yet to be designed. This paper describes the basic principles of vapor recovery systems as they pertain to inerted tankers. The Gaviota Marine Terminal Vapor Recovery System and other marine systems are briefly described. Complications caused by the impending local or national vapor recovery rules and remaining safety concerns are also discussed.

This paper provides the results of an experimental research on the performance of catalytic combustion of gasoline vapor. A packed bed reactor was built to test the effect of inlet temperature and concentration on catalytic combustion of gasoline vapor over Pd/Al2O3. The study shows that catalytic combustion is a cost-effective and environmental friendly method to control this kind of emission. The light-off temperature is quite low and full conversion rate is easy to achieve. Meanwhile, the method of controlling the bed temperature is proposed to avoid sintering if the technology is utilized in larger-scale equipment.

Bioethanol and dimetyl carbonate (DMC) are considered alternative fuels and additives to the synthesis compounds used now, since bioethanol is a biofuel and dimethyl carbonate (DMC) is non-toxic, biodegradable and can be produced in a cleaner way. In this study, the effect of adding dimethyl carbonate (DMC) and ethanol to gasoline on the volatility was investigated. The volatility was the main goal of this research but also, the effect on the antiknock properties was studied. Mixtures of gasoline with DMC or with bioethanol were prepared in different proportions of additive: 3%, 6% and 9% v/v. Additionally, mixtures with 3% v/v ethanol plus 3% or 6% v/v DMC, and3% DMC plus 6% v/v ethanol were prepared. For the volatility evaluation, the ASTM distillation curve and vapor pressure of these mixtures were determined experimentally in order to predict the performance of the resulting fuels. When adding oxygenated compounds, the increase in vapor pressure was proportional to the additive quantity. Additionally, modifications of the ASTM distillation curves were observed, with these indicating the formation of minimum boiling point azeotropes and the corresponding increase in volatility, with good effect on the ease of ignition in the engine. Based on the experimental results, the vapor lock index VLI, drivability index DI and vapor–liquid ratio temperature T(V/L=20) were calculated to quantify the volatility. The experimental results showed that gasoline mixtures with these oxygenated compounds show a significant increase in antiknock properties. Thus, for mixtures with ethanol, the research octane number (RON) increases by up to 2.2 units and the motor octane number (MON) increases by up to 1.2 units. Gasoline mixtures with DMC have another behavior: RON increased by up to 1.5 units, while the MON value increased by up to 2.5 units. For an initial gasoline with RON = 94.7 and MON 84.7, these increases are important and make the difference by exceeding the RON = 95 limit. Adding dimethyl carbonate to gasoline–ethanol blends improves the sensitivity of the fuel.

The evaporative emission control system (EVAP system) is the most commonly used strategy to limit the unburned petrol vapor emissions from a gasoline-fueled vehicle fuel tank, in order to comply with the international regulations on Volatile Organic Compounds (VOCs) emission. A carbon canister is used to collect and store the gasoline vapors generated in the tank, then it is purged by the engine intake manifold depression and the vapors are burned in the engine along with the fresh charge. In this activity, a 1.0 L carbon canister for European gasoline vehicles, provided by FCA, has been used for an experimental analysis, in order to characterize its adsorption and desorption behavior. A standard mixture of n-butane and nitrogen (40 g/h of n-butane, 50% vol. with nitrogen) has been used for loading the canister to breakthrough (2 g); canister purging has been performed with 3000 bed volumes of nitrogen flux at 25 L/min. Tests have been performed in FCA laboratories, at the Pomigliano Technical Center. Canister mass gain has been measured during the tests and after each test with a precision weight scale. Internal temperatures have also been measured by K-type thermocouples placed inside the carbon bed; due to the adsorption process, bed temperatures can reach 70 °C. After several tests, results on mass gain show an “aging” trend of the activated carbons.

In this article, we present the possibility of using terahertz time-domain spectroscopy to detect trace, ppm-level (%wt.) concentrations of admixtures in 95-octane lead-free gasoline in straightforward time-of-flight (pulse-delay) measurements performed directly in the liquid. The method was tested on samples containing 75–0.0125% of isopropanol and 0.3–0.0250% of water. The detection limits for isopropanol and water content were determined to be 125 ppm and 250 ppm, respectively, approaching the limits of much more complicated and time-consuming methods (like spectroscopy of the vapor phase). The measured pulse delays were compared with theoretical calculations using the modified Gladstone-Dale mixing rule for the solutions. The comparison demonstrated good agreement for gasoline-alcohol mixtures and large discrepancies for gasoline-water mixtures, suggesting that gasoline-water mixtures cannot be considered idealized binary mixtures. Our results clearly show that the pulse time delay measurement by THz-TDS is a fast and sensitive method of gasoline contamination detection and, as such, can be easily integrated with industrial online real-time quality control applications.

Current regulatory documents in Russia establish the need for testing laboratories to determine such parameters as saturated vapor pressure using the Reid method, air saturated vapor pressure, total vapor pressure of crude oil. In analytical practice, appropriate reference materials are used for measurement quality control, method validation, metrological traceability establishment, and other purposes. In addition, the calculation of various vapor pressure equivalents using correlation equations (DVPE – dry vapor pressure equivalent, RVPE – Reid vapor pressure equivalent, etc.) is regulated by appropriate methods for determining vapor pressure. Vapor pressure is a method-dependent parameter; so many producers of reference materials use interlaboratory experiment as a way to establish a certified value. Thus, when conducting an interlaboratory experiment in the process of certification of reference materials, it was revealed that laboratories can incorrectly interpret the obtained experimental data – consider values of the air saturated vapor pressure, total vapor pressure and even calculated vapor pressure equivalents as the Reid vapor pressure. To solve this problem, the authors of this work set the goal of assessing the equivalence of methods for determining the vapor pressure of oil and oil products used in testing laboratories in order to identify the key characteristics of the stated methods and assess their equivalence. The article discusses methods the vapor pressure determination using an automatic vacuum chamber and a Reid bomb. Various matrices of reference materials (hydrocarbons, gasoline, commercial oil, gas condensate) were investigated, and the calculated vapor pressure equivalents were obtained and compared. It was shown that the air saturated vapor pressure, dry vapor pressure equivalent, Reid vapor pressure equivalent, and total vapor pressure cannot be equated to the saturated vapor pressure values determined by the Reid method. A comparative assessment of methods for determining the vapor pressure of oil and oil products used in testing laboratories can be of assistance to developers of regulatory documents for oil, gas condensate, and motor gasoline, revealing the need to separate the requirements for vapor pressure parameters of the considered objects of analysis and providing empirical material.

Abstract Vehicle evaporative emission is one of the most important sources of pollution from a gasoline-fueled vehicle. Since international regulations on Volatile Organic Compounds (VOC) emission are becoming increasingly stringent every year, the study of the VOC generation has become of fundamental importance. It is known that VOC generation is particularly high during the refueling phase: fresh fuel coming from the refueling nozzle impacts on the filling pipe wall and it is a source for sloshing in the fuel tank. Fuel vapor generated can be collected by a vapor recovery nozzle and stored in the gas station tank (Stage II vapor recovery system, European normative) or trapped by the vehicle carbon canister (On-board Refueling Vapor Recovery system, U.S. normative). In this activity, an automotive gasoline fuel tank for U.S. applications has been used for both experimental and numerical analyses, provided by FCA. Experiments were performed in FCA laboratories, in a sealed and thermal controlled environment (mini-SHED): vapor flow exiting the fuel tank during refueling has been measured, and fuel vapor mass has been evaluated by dynamically measuring the weight variation of a carbon canister filter connected to the fuel tank vent system. A CFD model was built based on CAD geometries provided by FCA, and numerical analysis of the refueling process has then been executed by using a commercial 3D CFD software. Results were then compared with experimental data. This activity is a part of a collaboration between University of Naples Federico II and FCA Italy about fuel vapor emissions control and prediction.

A Cooperative Fuels Research (CFR) gasoline engine has been modified to run on computer controlled Port Fuel Injection (PFI) and electronic ignition. Additionally a fast acting sampling valve (controlled by the engine control computer) has been placed in the engine’s intake system between the fuel injector and cylinder head in order to measure the fuel components that are vaporizing in the intake port immediately after the fuel injection event, and separately during the intake valve open period. This is accomplished by fast sampling a small portion of the intake port gases during a specified portion of the engine cycle which are then analyzed with a gas chromatograph. Experimental mixture preparation results as a function of inlet port temperature and pressure are presented. As the inlet port operates at higher temperatures and lower manifold pressures more of the injected fuels’ heavier components evolve into the vapor form immediately after fuel injection. The post-fuel injection fuel-air equivalence ratio in the intake port is characterized. The role of the fuel injection event is to produce from 1/4 to slightly over 1/2 of the combustible fuel-air mixture needed by the engine, as a function of port temperature. Fuel vapor sampling during the intake valve open period suggests that very little fuel is vaporizing from the intake port puddle below the fuel injector. In-cylinder fuel vapor sampling shows that significant fuel vapor generation must occur in the lower intake port and intake valve region.

Abstract Despite efficiency and emission benefits, the Gasoline Compression Ignition (GCI) technology faces a key technical risk of deteriorated cold start performance. This study aims to provide experimental dataset and analysis of fuel sprays under ultra-low temperature (as low as −40 °C) adapted for GCI applications. Both RON92 gasoline and ultra-low sulfur diesel (ULSD) were tested in this study to investigate the effects of fuel properties and ambient conditions on the spray vaporization and mixing processes. The experiments were conducted in a constant-volume combustion vessel with various fuel temperatures, injection pressures, ambient densities, and charge gas temperatures, captured by simultaneous Mie scattering and schlieren imaging. A novel fuel chilling setup was introduced to control the fuel reservoir temperature by circulating of liquid-nitrogen-cooled methanol. Vapor penetration, liquid penetration, and spray cone angle from a heavy-duty multi-hole injector were obtained through image processing. The results showed comparable vapor penetration between RON92 and ULSD even with different fuel temperatures and charge gas temperatures. However, RON92 and ULSD differs in terms of liquid penetration at different ambient charge gas temperatures due to their different volatility. RON92 gasoline started to present saturated liquid length at 700K, while ULSD needed a higher temperature at 900K. A semi-quantitative analysis was practiced using single component surrogates to highlight the fuel volatility effect.

Abstract Petrol vapor emissions are the main source of pollution for both standard and hybrid vehicles. They are mainly generated by gasoline evaporation from the fuel tank of both running and parked vehicles; it is mostly driven by fuel temperature variation due to daily temperature changes (if parked) and heat from engine (if running). To prevent its dispersion in the environment, the vapor generated in the fuel tank is usually stored in a carbon canister filter that must be periodically “purged” in order to prevent its saturation, by venting it to the intake manifold. Canister management, made by the Engine Control Unit (ECU), becomes even more critical for hybrid-electric vehicles because thermal engine is often off, thus purging cannot take place. A pressurized fuel tank is often used for hybrid applications, to further isolate vapor from environment, making the fuel system even more complex to model. System design optimization is usually based on experience and experimental correlations, which require time and cost. Thus, comes the need for a comprehensive predictive model useful for both vehicle components (fuel tank and carbon canister) and ECU software design. A 0D Matlab® model is proposed, which can predict vapor generation from an arbitrary tank in standard and arbitrary thermal cycles, with arbitrary tank capacity, geometry and construction and at different filling levels. It is based on a system of thermo-fluid-dynamic differential equations and semi-empirical correlations that is iteratively solved in time. Model calibration has been performed by using a small size test tank and validation has been completed on full size tanks for both standard and hybrid-electric applications. The main driving force for vapor generation has been shown to be the amount of empty volume on top of the tank; other significant effects come from tank volume, material, external surface as well as fuel properties. Ongoing work is to develop and integrate a carbon canister loading/purging model, with the aim to build a full model of the vapor system.

Gasoline oxygenating agents (alcohols, ethers and a carbonate) were used to formulate gasoline at different oxygencontents up to 20 wt.% and compared with commercial Premium gasoline.The performance of each fuel was investigated in a port fuel injected, single cylinder, spark-ignited engine at different stages i.e. air fuel mixture preparation, combustion behavior and exhaust emissions. In all cases, the intake cooling effect (related mainly to fuel properties like latent heat of vaporization and Reid Vapor Pressure), shows an important relationship with engine performance and emissions, probably due to reductions in heat losses associated with decreases in charge temperature at compression stroke before ignition. This results was confirmed by means of vehicle FTP-75 test.The high RVP promotes high intake manifold evaporation rate, and the high HoV is related to important cooling effect as the fuel absorbs heat during evaporation. If the fuel evaporates faster upstream intake valves, the advantages of high HoV as a way to reduce compression work and heat transfer fallen.The quantification of the charge cooling effect was done by means of precision intake air temperature control and the instrumentation of a temperature downstream the injector at intake port and as close as possible to the intake valves.The use of oxygenates reduce the hydrogen and carbon fuel contents as a result of fuel dilution. For a given level of oxygenation as lower is the molecular oxygen content in the additive, higher will be the fuel dilution.For 10 wt.% oxygen and more, fuel performance in port engines depends mainly on oxygenate contents and its relationship with HoV and RVP. For oxygenated gasolines, fuel sensitivity have a direct relationship with latent heatls increase RON. In the other hand, MON is almostinsensible to high heat of vaporization, because the intake air is heated to 159 C as a test requirement.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4855

The importance of safety regulations and risk assessments in the chemical process of industry has been doubled by the increasing number of accidents in petroleum storage facilities. Control of critical situations and conditions against risks require appropriate planning, collection of valid information of possible scenarios and utilization of proper assessment techniques. In this study, by combining numerical simulation techniques, mathematical and experimental data and utilization of commercial software, the risks of a Tabriz refinery gasoline tank (as a case study) are investigated for a total release of the reservoir scenario within a specified period of time, as the worst case. The effect of the environment temperature is evaluated on the progression of the scenario. Based on comparison of the results of numerical simulations of pool fire, and vapor cloud explosion with simulation results based on empirical-mathematical models, it can be concluded that, there are significant differences between the results in the vicinity of the boundary conditions; however, with increasing distance from the center of the accident point, this difference decreases markedly.

Switching type exhaust gas oxygen sensors are critical to the performance of air-to-fuel ratio control in stoichiometric SI engines. Controlling the air-to-fuel ratio around stoichiometry is necessary for adequate three-way catalyst performance to meet government emissions regulations. However, the feedback signal from the sensor does not always truly depict the actual chemical mixture present in the exhaust gasses, which intrinsically affects the catalyst performance. A sensor may not provide correct air-to-fuel ratio feedback due to certain species in the exhaust gas which affect the equivalence ratio that the sensor switches from the high to low voltage or vice versa. This work attempts to characterize the impact of gas on fresh and aged sensors and builds upon earlier work in the field by using real engine exhaust rather simulated exhaust gas. In these experiments, the air-to-fuel ratio of a stoichiometric gasoline engine is incrementally increased from a lean to rich mixture to elicit the full switching response of the oxygen sensor. Additional sensor output curves are generated in the presence of external additive gases such as hydrogen, carbon monoxide, propane, and gasoline vapor. An automotive emissions analyzer and a hydrogen analyzer detect the concentrations of the exhaust gases and the chemical equivalence ratio is calculated using a carbon balance. This equivalence ratio creates a reference to examine the accuracy of the switch point of the sensor to actual stoichiometry. Using these data sets, it is possible to determine observe the effect of various gas species on the air to fuel ratio at which the sensor switches. The sensitivity of the different sensors to gas concentrations are quantified and presented, which form an elementary model to predict the sensor switch point in the presence of these gas species. Primary findings indicate that the impact of species on the sensor switch point is linearly related to the concentration of the species; sensor type and sensor age have an effect on a sensor's sensitivity to species; and different hydrocarbon species affect sensors differently. The findings support the simulated exhaust gas results reported in the literature in that the degree of interference of a species is related to the diffusion rate of the species with respect to oxygen through the sensor. The results also point toward the importance of the species of hydrocarbons in the engine exhaust, which are uncontrolled and can vary with engine operating conditions. This feature is critical to the application of this knowledge to automotive control.

Precise control of the spray behavior is key to fully realize the potential benefits of modern GDI engines. Flash boiling is known to alert the spray behavior significantly; and thus, a complete understanding of its mechanism is essential. In this work, a study of the effect of the fuel properties on the near-nozzle flow characteristics of a single-hole GDI injector under the flash boiling conditions is presented. The performance of hexane and a typical gasoline surrogate iso-octane has been studied both experimentally and numerically. Fuel temperature varied from 20 and 100 °C with ambient pressures of 20, 50 and 100 kPa. For the experiment, microscopic imaging was conducted with a high-speed camera coupled with a long-distance microscope; and a convex lens was used to provide enough illumination to the interested area. The numerical studies were performed at the maximum needle lift using OpenFOAM, an open-source Computational Fluid Dynamics (CFD) code. Phase change was captured with the Homogeneous Relaxation Model (HRM); and turbulence was modeled using RNG k–ε model. The results have shown that while the near-field flow behavior of hexane and isooctane was similar under ambient conditions, a significant difference was observed between the two under the flash boiling conditions. The onset and development of flash boiling of isooctane was retarded compared to hexane due to its much lower vapor pressure. Spray contraction has been observed in the down-stream due to fuel vaporization and air entrainment. The CFD results were shown to agree well with the experimental data.

The high-response diagnostic complex for remote control and analyses of droplets and vapors of mazut, oil, gasoline, kerosene, diesel fuel and liquefied natural gas in the clouds and turbulent aerosolflows in the atmosphere with volume up to 107 m3 is described.

En el transcurso del primer semestre de 2023 la economía colombiana continuó avanzando en el proceso de ajuste requerido para corregir los desequilibrios macroeconómicos y controlar las presiones inflacionarias acumuladas tras los diversos choques de oferta y la rápida expansión de la demanda durante 2021 y 2022, la cual superó el crecimiento potencial de la economía. El ajuste económico en curso ha sido posible gracias a la moderación del crecimiento de la demanda interna y a la progresiva disolución de los choques de oferta que elevaron los costos de producción. La demanda interna comenzó a desacelerase en los últimos meses de 2022 y se contrajo un -0,2 % en el primer trimestre de este año, debido al menor crecimiento del consumo de los hogares y a la caída de la formación bruta de capital. Por su parte, los menores precios internacionales de las materias primas, la paulatina normalización de las cadenas de suministro y la apreciación de la tasa de cambio han contribuido a disipar los choques de oferta, lo cual se ha reflejado en una disminución de la inflación anual de precios al productor desde un nivel del 19,2 % a finales de 2022 al 4,7 % en junio de 2023 1. El menor dinamismo de la demanda interna se ha venido reflejando en una desaceleración progresiva de la actividad económica. Es así como en el primer trimestre de 2023 el PIB registró un crecimiento anual del 3,0 %, ritmo equivalente a una tercera parte del crecimiento promedio anual que se observó durante los tres primeros trimestres de 2022 (9,1 %). Según el indicador de seguimiento de la economía (ISE) que elabora el DANE, esta pérdida de dinamismo continuó en abril y mayo, al registrarse variaciones de ese indicador del -0,8 % y 0,6 %, respectivamente, frente a los mismos meses de 2022. Estos resultados fueron inferiores a lo observado en marzo (1,4 %), en la serie del ISE ajustada por efecto estacional y calendario. Ello apunta a que el crecimiento del PIB seguirá declinando en el segundo trimestre, lo cual es coherente con el pronóstico de crecimiento del PIB ligeramente inferior al 1,0 % para 2023 elaborado por el equipo técnico. A pesar de la desaceleración económica en curso, el mercado laboral sigue mostrando fortaleza, como se deduce del continuo descenso de la tasa de desempleo en el agregado nacional hasta el trimestre móvil terminado en mayo (10,4 %), su valor más bajo desde el inicio de la pandemia del covid-19 2. La desaceleración de la actividad económica es un fenómeno que se anticipaba, en parte, como resultado de la política monetaria restrictiva que adoptó el Banco de la República para controlar las presiones inflacionarias. A la menor actividad económica también estaría contribuyendo una política fiscal menos expansionista que en 2022, según se contempla en los pronósticos presentados en el Marco Fiscal de Mediano Plazo de 2023 (MFMP-23). A esto se añadió una desaceleración de la demanda externa relevante para el país debido al menor crecimiento de los socios comerciales, en un contexto internacional de altas tasas de interés de política monetaria, tasas de inflación por encima de sus metas y elevada incertidumbre generada por la prolongación de la invasión de Rusia a Ucrania. La Junta Directiva del Banco de la República (JDBR) ha sido reiterativa en sus diversas comunicaciones sobre la necesidad de adelantar este proceso de ajuste, para lograr el retorno gradual de la inflación a la meta del 3 %, corregir los desequilibrios macroeconómicos y asegurar la sostenibilidad del crecimiento económico en el largo plazo. La responsabilidad constitucional que recae sobre el Banco de la República, sobre la cual se hizo énfasis en el pasado Informe al Congreso, exige mantener una inflación baja y estable en consonancia con la política económica en general, de manera que permita apoyar un crecimiento económico sostenible y un balance externo financiable. Las decisiones de política monetaria se han adoptado con el respaldo de la sólida base institucional y técnica que soporta el esquema de inflación objetivo, cimentada en la experiencia acumulada durante más de dos décadas por el banco central. Los motivos específicos que ha tenido la JDBR para emprender un proceso de ajuste monetario, el más fuerte desde que el Banco de la República adoptó la estrategia de inflación objetivo, han sido complejos y de diversa índole. Las presiones inflacionarias provinieron inicialmente de choques de oferta de origen externo e interno que presionaron al alza los costos y precios de los alimentos y otros productos de consumo, a las cuales se agregaron presiones de origen cambiario. Estos choques llevaron a un incremento de las expectativas de inflación, lo cual desató un proceso de indexación de precios, que se exacerbó debido a los excesos de demanda que surgieron en 2022. La respuesta de la política monetaria mediante el incremento de las tasas de interés buscaba reducir los excesos de demanda, contener el aumento de las expectativas y limitar los efectos de la indexación de precios. Todo ello crea las condiciones propicias para permitir que, a medida que los choques de oferta cedan y se alivien, y con ello las presiones de costos, la inflación empiece a reducirse. Este es un proceso que se cumple con cierto rezago, pero que, dado el tiempo que la política monetaria lleva actuando, ya se ha empezado a producir, como lo mostró la reciente disminución de la tasa de inflación y la revisión a la baja de sus expectativas a diferentes plazos. Acorde con el mandato constitucional de asegurar una coordinación de la política monetaria con la política económica general, además de mitigar las presiones inflacionarias, el ajuste monetario viene cumpliendo el propósito de corregir los desequilibrios macroeconómicos que ponen en riesgo la estabilidad de la economía colombiana. Al respecto, no cabe duda de que el crecimiento del PIB del 7,3 % en 2022 fue sobresaliente, al haber más que duplicado el crecimiento mundial (3,5 %) y superado ampliamente la expansión de América Latina y el Caribe (3,9 %), según cifras del FMI. Un dinamismo económico tan elevado trae importantes ganancias de bienestar, en particular cuando permite reducir las tasas de desempleo, como ha venido ocurriendo en Colombia; sin embargo, es un crecimiento insostenible en tanto se fundamenta en una situación fiscal ampliamente deficitaria y en un preocupante incremento en el endeudamiento de los hogares. Ello generó un exceso de demanda agregada que no solo presionó al alza la inflación y sus expectativas, sino que también amplió el déficit de la cuenta corriente de la balanza de pagos a niveles históricamente altos durante varios años. El déficit de la cuenta corriente aumentó desde un nivel del 5,6 % del PIB en 2021, que ya era elevado, a uno del 6,2 % del PIB en 2022, uno de los más altos observados en Colombia. La ampliación del desbalance externo en 2022 se produjo en un año en el que los precios internacionales del petróleo, el carbón y el café se mantuvieron en niveles favorables, lo que contribuyó al buen desempeño de las exportaciones. No obstante, para cubrir los faltantes de oferta, la economía incrementó de manera importante su demanda de importaciones, impidiendo una reducción del desbalance externo. Como consecuencia, la economía colombiana recurrió a un mayor endeudamiento externo, bien sea como flujo de inversión de portafolio o como endeudamiento directo. Todo esto muestra la vulnerabilidad que significa para la economía mantener un nivel de gasto que supera significativamente sus ingresos. La política monetaria restrictiva, junto con el aumento en la carga tributaria, han venido induciendo un ajuste progresivo de estos desequilibrios. La desaceleración de la demanda interna iniciada a partir del cuarto trimestre de 2022 ocurrió de la mano de una moderación del consumo de los hogares, cuyo crecimiento en el primer trimestre de 2023 fue del 3,0 %, comparado con un incremento del 9,5 % en 2022. Esto último se ha reflejado en una desaceleración del crédito de consumo, que pasó de crecer desde un ritmo cercano al 23 % anual a finales del tercer trimestre del año anterior, a algo menos del 7,0 % anual a mediados de junio de 2023. De haberse continuado con una expansión tan rápida del crédito de consumo, se habría podido generar una situación insostenible sobre la capacidad de pago de los hogares. Asimismo, la formación bruta de capital, que tuvo un desempeño sobresaliente en 2022, empezó a mostrar ajustes en sus principales componentes. La principal fuente de dicha corrección ha sido la inversión en maquinaria y equipo, que en el primer trimestre del año presentó caídas tanto en términos trimestrales como anuales, principalmente en el rubro de equipo de transporte. A la par con el avance en la corrección de los desequilibrios macroeconómicos, la inflación total interrumpió la tendencia creciente que mantuvo hasta marzo de 2023. En efecto, luego de alcanzar un nivel del 13,1 % al cierre del año anterior, la inflación total se mantuvo estable alrededor del 13,3 % durante los primeros tres meses de 2023, y a partir de abril empezó a descender, para ubicarse en 12,1 % en junio. Los alimentos han sido el rubro que más ha contribuido a este cambio de tendencia, al haber reducido su variación anual del 27,8 % en diciembre pasado al 14,3 % en junio. Esta variación ha sido compensada en alguna medida por el incremento de la inflación de regulados, debido a los sucesivos aumentos en los precios de la gasolina. Por su parte, la inflación básica (sin alimentos ni regulados) continúa mostrando rigidez, al ubicarse en el 10,5 % en junio, lo que refleja procesos de indexación de precios. La subcanasta de servicios ha sido especialmente afectada por el fenómeno de indexación, a lo cual se han agregado las presiones de costos laborales, el aumento en los precios de los alimentos que han presionado al alza las comidas fuera del hogar y la elevada demanda por servicios de entretenimiento. Este comportamiento debería ir cediendo a medida que los efectos de la política monetaria terminen por transmitirse a la economía, y la tendencia decreciente de la inflación se refleje en una revisión a la baja de las expectativas de variación de precios por parte del público. Así lo prevén los pronósticos del equipo técnico y las expectativas del mercado que anticipan una inflación decreciente durante los próximos dos años. ____________________________________________________________ 1 Corresponde a la variación anual del IPP de oferta interna. 2 Al cierre de este Informe se conocieron los datos de la Gran Encuesta Integrada de Hogares de junio, con los cuales la tasa de desempleo se mantuvo estable en su medición desestacionalizada del agregado nacional para el trimestre móvil (10,3 %), aunque con una reducción para el dato puntual de junio