Article

Effects of Air Conditioner Use on Real-World Fuel Economy

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  • MMM Services, LLC
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Abstract

On-road and laboratory experiments with a 2009 Ford Explorer and a 2009 Toyota Corolla were conducted to assess the fuel consumption penalty associated with air conditioner (A/C) use at idle and highway cruise conditions. Vehicle data were acquired on-road and on a chassis dynamometer. Data were gathered for various A/C settings and with the A/C off and the windows open. At steady speeds between 64.4 and 113 kph (40 and 70 mph), both vehicles consumed more fuel with the A/C on at maximum cooling load (compressor at 100% duty cycle) than when driving with the windows down. The Explorer maintained this trend beyond 113 kph (70 mph), while the Corolla fuel consumption with the windows down matched that of running the A/C at 121 kph (75 mph), and exceeded it at 129 kph (80 mph). The incremental fuel consumption rate penalty due to air conditioner use was nearly constant with a slight trend of increasing consumption with increasing vehicle (and compressor) speed. A lower fuel penalty due to A/C operation is observed at idle for both vehicles, likely due to the low compressor speed at this operating point, although the percentage increase due to A/C use is highest at idle.

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... The fuel-use penalty from AC was 90% at idle, and decreased from 35% to 9% at constant speed as speed increased (8). Huff et al. measured a 2009 MY Toyota Corolla and a 2009 MY Ford Explorer on a dynamometer at idle and at selected steady-speeds with and without AC operation (17). The largest FE penalty was during idle, which averaged 60% for the two vehicles. ...
... In laboratory-based dynamometer measurements, the approach to estimate the effect of AC on FE is to measure the FE of a vehicle with and without AC operation for a given cycle, or at specified speed (7,8,17). The reduction in FE is the FE penalty from AC, expressed as % reduction compared with the baseline FE without AC operation. ...
... For Mode 3, which includes idle, the ACon vehicles had 13% statistically significantly higher fuel-use rate than the AC-off vehicles. Thus, the AC effect on fuel-use is the largest during idling, as expected from Huff et al. (17). In relation to absolute difference, the fleet-average increase in real-world fuel-use rate during idling is 0.05 g/s. ...
Article
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With more stringent U.S. fuel economy (FE) standards, the effect of auxiliary devices such as air-conditioning (AC) have received increased attention. AC is the largest auxiliary engine load for light duty gasoline vehicles (LDGVs). However, there are few data regarding the effect of AC operation on FE for LDGVs based on real-world measurements, especially for recent model year vehicles. The Motor Vehicle Emission Simulator (MOVES) is a regulatory model for estimating on-road vehicle energy-use and emissions. MOVES adjusts vehicle energy-use rates for AC effects. However, MOVES-predicted FE with AC has not been evaluated based on empirical measurements. The research objectives are to quantify the LDGVs FE penalty from AC and assess the accuracy of MOVES2014a-predicted FE with AC. The AC effect on real-world fleet-average FE was quantified based on 78 AC-off vehicles versus 55 AC-on vehicles, measured with onboard instruments on defined study routes. MOVES2014a-based FE penalty from AC was evaluated based on real-world estimates and chassis dynamometer-based FE test results used for FE ratings. The real-world FE penalty ranges between 1.3% and 7.5% among a wide range of driving cycles. Fuel consumption at idle is 13% higher with AC on. MOVES underestimates the real-world FE with AC by 6%, on average. MOVES overestimates the AC effect on cycle-average FE ranging between 13.5% and 18.5% for real-world and MOVES default cycles, and between 11.1% and 14.5% for standard cycles.
... In a previous study [1] on-road and chassis dynamometer-based experiments with a 2009 Ford Explorer and a 2009 Toyota Corolla were conducted to assess fuel consumption penalties due to air conditioner (A/C) use at idle and highway cruise conditions. Experiments included these vehicles operating with various A/C settings, with the A/C off, and with A/C off and windows open. ...
... Experiments included these vehicles operating with various A/C settings, with the A/C off, and with A/C off and windows open. The purpose was to better understand the actual fuel penalty due to A/C use and fuel penalty trade-off between driving using the A/C versus driving with the windows down [1]. A major portion of the previous effort involved running the A/C at maximum cooling which generates the maximum fuel penalty; clearly the fuel penalty from A/C usage is highly variable and dependent on many factors. ...
... A major portion of the previous effort involved running the A/C at maximum cooling which generates the maximum fuel penalty; clearly the fuel penalty from A/C usage is highly variable and dependent on many factors. Notable results from this previous study [1] During peer review of the previous study, some reviewers questioned the usefulness of examining 100% A/C duty cycle, suggesting it would be unrealistically high. Obviously 100% duty cycle is the high endpoint of A/C operation, and much A/C use involves lower duty cycles. ...
Technical Report
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Air conditioner usage was characterized for high heat-load summer conditions during short driving trips using a 2009 Ford Explorer and a 2009 Toyota Corolla. Vehicles were parked in the sun with windows closed to allow the cabin to become hot. Experiments were conducted by entering the instrumented vehicles in this heated condition and driving on-road with the windows up and the air conditioning set to maximum cooling, maximum fan speed and the air flow setting to recirculate cabin air rather than pull in outside humid air. The main purpose was to determine the length of time the air conditioner system would remain at or very near maximum cooling power under these severe-duty conditions. Because of the variable and somewhat uncontrolled nature of the experiments, they serve only to show that for short vehicle trips, air conditioning can remain near or at full cooling capacity for 10-minutes or significantly longer and the cabin may be uncomfortably warm during much of this time.
... However, A/C systems operate via a vapour compression system in which the compressor draws power from the engine. As a result, fuel consumption and CO2 tailpipe emissions increase significantly during A/C use (Benouali et al., 2003;Farrington and Rugh, 2000;Huff et al., 2013;Lee et al., 2013). Another problem car is parked in direct sunlight, whereupon the internal cabin temperature may reach as high as 70°C (Basar et al., 2013;Jasni and Nasir, 2012). ...
... A similar study shows that fuel consumption for a sedan increases by 20-25% when using the A/C system (Bharathan et al., 2007). Even at low engine speeds (idling), more fuel is wasted than at medium and high speeds (Huff et al., 2013;Lee et al., 2013). ...
Article
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This paper presents a new concept for air-conditioning systems in Liquefied Petroleum Gas (LPG) fuelled vehicles, a ½ cycle refrigeration system. Prior to being used in an engine as a fuel, LPG serves as a refrigerant. Harvesting of cooling from LPG was carried out by an auxiliary evaporator. Initially, to evaporate LPG in an Original Equipment Manufactured (OEM) of vaporizer, water coolant is used. In these systems, the thermal energy to evaporate LPG is obtained from air driven by an electric blower. Cold air exiting from the evaporator may then be supplied to the cabin. The test results show that the actual cooling effect produced is as high as 1.2 kW for a LPG flow rate of more than 3 g/s and an air mass flow rate of 16 g/s. In conclusion, the ½ cycle air conditioning system is a promising application for LPG-fuelled vehicles to reduce the load on air-conditioning systems.
... Namun demikian, selama sistem AC bekerja dengan sistem kompresi uap, sistem akan mengambil tenaga dari mesin untuk menggerakkan kompresor. Hal ini meningkatkan konsumsi bahan bakar dan emisi gas buang (Farrington & Rugh, 2000;Huff, West, & Thomas, 2013;J. Lee, Kim, Park, & Bae, 2013). ...
... Sebuah studi yang sama menunjukkan bahwa konsumsi bahan bakar untuk mobil sedan meningkat 20-25% saat sistem AC dioperasikan (Bharathan et al., 2007). Bahkan pada kecepatan mesin rendah (idling), lebih banyak bahan bakar yang dipakai dibandingkan dengan saat mesin beroperasi pada putaran sedang dan tinggi (Huff et al., 2013;J. Lee et al., 2013). ...
Thesis
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Sistem Air Conditioning (AC) telah menjadi aksesoris utama pada pada kendaraan untuk meningkatkan kenyamanan berkendaraan. Namun demikian, selama sistem AC bekerja dengan sistem kompresi uap, akan mengambil tenaga dari mesin untuk menggerakkan kompresor. Hal ini meningkatkan konsumsi bahan bakar hingga 21-53%. Sementara itu, kendaraan berbahan bakar LPG menyediakan potensi pendingin langsung (direct refrigeration) dari perubahan fase LPG pada perangkat vaporizer Potensi ini belum dimanfaatkan dan hilang melalui engine coolant. Oleh karena itu, penelitian ini fokus pada karakteristik direct refrigeration (potensial dan aktual) yang dihasilkan dari penguapan LPG tersebut untuk pendinginan kabin mobil. Penelitian ini terdiri dari empat tahapan utama. Pertama, pengujian komposisi LPG dengan Gas Chromatography-Mass Spectromety (GC-MS). Kedua, simulasi energy delivery dan potensi efek pendinginan pada evaporator dengan data yang diperoleh dari GC-MS. Ketiga, validasi efek pendinginan aktual pada berbagai variasi laju aliran massa LPG dan tekanan evaporasi. Terakhir, perhitungan COP direct refrigeration (COPDR). Hasil penelitian ini menunjukan bahwa: 1) LPG yang keluar dari tangki selama proses pengosongan tangki menunjukkan bahwa komposisi molekul propane dan butane 2-methyl tidak konstan selama proses pengosongan tangki. Namun demikian, perubahan komposisi LPG tidak berpengaruh signifikan terhadap efek pendinginan yang dihasilkan, selama LPG yang mengalir dalam fuel line (sebelum diekspansikan) berbentuk cairan; 2). Semakin tinggi tekanan penguapan LPG dalam evaporator dan semakin besar laju aliran massa LPG, semakin besar efek pendinginan yang dihasilkan. Namun demikian, efek pendinginan yang dihasilkan adalah tidak linier dengan kenaikan laju aliran massa LPG karena keterbatasan area transfer kalor pada evaporator. Hasil pengujian menunjukkan efek pendinginan maksimal yang dapat dibangkitkan adalah sebesar 1,2 kW. Dengan beban pendinginan sebuah mobil penumpang berkisar antara 3-6 kW, ini berarti bahwa efek pendinginan dari sistem bahan bakar LPG memberikan kontribusi pada sistem AC hingga 40% untuk kendaraan dengan beban pendinginan 3 kW dan 20% untuk kendaraan dengan beban pendinginan 6 kW; dan 3) Pada kasus Direct refrigeration, COPDR dihitung dengan membandingkan efek refrigerasi dengan kerja kompresi untuk menghasilkan LPG cair bertekanan. Hasil perhitungan COPDR menurun ketika laju aliran massa LPG ditingkatkan dan COPDR meningkat ketika tekanan evaporasi dinaikkan. Nilai COPDR tertinggi adalah 6,27 yang diperoleh pada laju aliran massa LPG 1 g/s dan tekanan evaporasi 0,15 MPa. Sebagai kesimpulan, konsep direct refrigeration pada kendaraan dengan bahan bakar LPG sangat menjanjikan untuk dikembangkan sebagai sistem hibrida dengan sistem AC.
... A similar study showed that fuel consumption with AC operation for sedans increased 20-25% [31]. Even, when the engine operates at idling, the wasted fuel for the A/C system more than at medium speed and high speed [32,33]. In another study, the wasted fuel due to the use of A/C systems for cabin cooling in Europe accounted for 3.2% of total global fuel consumption [34]. ...
Article
Full-text available
In LPG-fuelled vehicles, there is a potential cooling from LPG evaporation in the fuel line. Cooling power is obtained without reducing the caloric value of the fuel supplied to the engine. Thus, LPG functions like a refrigerant before it is burned in the combustion chamber. Consequently, there is a change in fuel efficiency. Therefore, this paper presents a new thermodynamic analysis of LPG-fuelled vehicles by harvesting cooling power in the fuel line. The research was conducted by simulating LPG mass flow rates of 1-6 g/s on 1998 cm 3 engine which represent the fuel consumption of passenger cars. The total fuel efficiency is calculated by summing the indicated thermal power added by cooling power to the fuel energy supplied. The results show that the cooling power from the fuel line can increase the total fuel efficiency of 3.16%.
... It was estimated that 13.5 billion litres fuel (or 3% fuel consumption) could be saved in the US by reducing the use of air conditioners by 50% [82]. Experimental results showed that a small passenger car consumed more fuel with maximum cooling than with windows-down when cruising speed was between 64 and 113 km/h [83]. However, fuel consumption with windows-down overtook air conditioner at 129 km/h due to the increased aerodynamic drag. ...
Article
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Road transport consumes significant quantities of fossil fuel and accounts for a significant proportion of CO2 and pollutant emissions worldwide. The driver is a major and often overlooked factor that determines vehicle performance. Eco-driving is a relatively low-cost and immediate measure to reduce fuel consumption and emissions significantly. This paper reviews the major factors, research methods and implementation of eco-driving technology. The major factors of eco-driving are acceleration/deceleration, driving speed, route choice and idling. Eco-driving training programs and in-vehicle feedback devices are commonly used to implement eco-driving skills. After training or using in-vehicle devices, immediate and significant reductions in fuel consumption and CO2 emissions have been observed with slightly increased travel time. However, the impacts of both methods attenuate over time due to the ingrained driving habits developed over the years. These findings imply the necessity of developing quantitative eco-driving patterns that could be integrated into vehicle hardware so as to generate more constant and uniform improvements, as well as developing more effective and lasting training programs and in-vehicle devices. Current eco-driving studies mainly focus on the fuel savings and CO2 reduction of individual vehicles, but ignore the pollutant emissions and the impacts at network levels. Finally, the challenges and future research directions of eco-driving technology are elaborated.
... Assuming a truck has the same driving cycles shown in Fig. 2, the variation in its GHG emission due to temperature, truck weight, road grade, and year is illustrated in Fig. 4. Operating air conditioner at high temperature reduces vehicle (Huff et al. 2013). Heavier truck weights, and steeper road grades reduce fuel economy of vehicle, and vice versa. ...
Article
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Purpose Fuel economy and emissions of heavy-duty trucks greatly vary based on vehicular/environmental conditions. Large-scale infrastructure construction projects require a large amount of material/equipment transportation. Single-parameter generic hauling models may not be the best option for an accurate estimation of hauling contribution in life cycle assessment (LCA) involving construction projects; therefore, more precise data and parameterized models are required to represent this contribution. This paper discusses key environmental/operational variables and their impact on transportation of materials and equipment; a variable-impact transportation (VIT) model accounting for these variables was developed to predict environmental impacts of hauling. Methods The VIT model in the form of multi-nonlinear regression equations was developed based on simulations using the U.S. Environmental Protection Agency (EPA)’s Motor Vehicle Emission Simulator (MOVES) to compute all the impact categories in EPA’s TRACI 2.1 and energy consumption of transportation. Considering actual driving cycles of hauling trucks recorded during a pavement rehabilitation project, the corresponding environmental impacts were calculated, and sensitivity analyses were performed. In addition, an LCA case study based on historical pavement reconstruction projects in Illinois was conducted to analyze the contribution of transportation and variability of its impacts during the pavements’ life cycle. Results and discussion The importance of vehicle driving cycles was realized from simulation results. The case study results showed that considering driving cycles using the VIT model could increase the contribution of hauling in total life cycle Global Warming Potential (GWP) and total life cycle GWP itself by 2–4 and 3–5%, respectively. In addition to GWP, ranges of other hauling-related impact categories including Smog, Ozone Depletion, Acidification, and Primary Energy Demand from fuel were presented based on the case study. Ozone Depletion ranged from 9 to 45%, and Smog ranged from 11 to 48% of the total relevant life cycle impacts. The GWP contribution of hauling in pavement LCA ranged between 5 and 32%. The results indicate that the contribution of hauling transportation can be significant in pavement LCA. Conclusions For large-scale roadway infrastructure construction projects that need a massive amount of material transportation, high fidelity models and data should be used especially for comparative LCAs that can be used as part of decision making between alternatives. The VIT model provides a simple analytical platform to include the critical vehicular/operational variables without any dependence on an external software; the model can also be incorporated in those studies where some of the transportation activity data are available.
... During the idle condition of engine vehicles, fuel consumption increases to a maximum level of 90% while using AC, compared to without using AC [82]. Another study found that, at high temperatures, fuel consumption can increase by 25%, but during idle conditions, fuel consumption increased by 60% while using AC, compared to without using AC [83]. Due to the movement of the vehicle, an extra artificial convection effect could be the aim of future development, one that is around the vehicle, in comparison with the idle and stationary cases [84]. ...
Article
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Environmental protection initiatives are speeding up the replacement of the present IC engine-based transportation system with an electric motor-driven system. In electric vehicles (EV), energy stored in batteries is used for the traction of the vehicle and the operation of the auxiliaries. The range of the electric vehicle was identified to be one of the major challenges faced by the EV segment. The optimization of the consumption of stored energy is the best solution for range improvement in an EV. Auxiliaries in the vehicle include basic accessories such as a lighting system and equipment for improved comfort such as air conditioners. Air conditioning equipment is the major power-consuming auxiliary in an EV apart from the traction motor. This review article discusses the significance and influence of different components of the air conditioning system, and methods followed by researchers to optimize the performance and reduce the energy consumption of the air conditioning system to extend the range of vehicles. The effects of thermal load and volume of space to be conditioned were also considered in this study. This review concludes by stating the different possibilities for the reduction in power consumption and emphasizes zonal air conditioning of occupant space as a solution for reducing energy consumption or increasing the range of EVs. Compared to full-space air conditioning, zonal AC can reduce power consumption by up to 51%.
... In a similar study, Bharathan et al. [22] found that fuel waste due to the AC system load was around 20-25%. More relevant increases are quoted in the literature when the vehicle operates at low engine speeds [23,24]. ...
Article
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Alternative fuels have become an effective solution to reduce the impact of road transport on the environment. On the other hand, the growing uses of airconditioning (AC) have contributed to worsening the fuel economy of passenger vehicles. Liquid petroleum gas (LPG), if injected in the gaseous phase to power SI engines, may allow reducing the fuel consumption due to AC devices through the recovery of cooling energy from the fuel systems. This paper presents lab-scale tests of an air conditioning system prototype for LPG-fuelled vehicles. The prototype has been assembled using standard vehicle components to quantify the cooling energy recoverable from the LPG evaporation before the fuel is injected into the engine intake manifold. Temperature and humidity of the air exiting the LPG evaporator are measured for fuel mass flow rates typical of light-duty vehicles. The energy efficiency ratio (EER) of the prototype achieves 2.72 when cooling power equals 1.2 kW. Although the system tested needs improvements, the experimental data show that the cooling energy recovered by LPG evaporation can significantly reduce the power consumption of standard AC systems in passenger cars.
... The addition of chargers in public locations is predicted to stimulate the local economy through the promotion of PEV uptake, which is limited by customer range anxiety. In addition, the US Department of Energy advises that hot weather decreases vehicle efficiencies by upwards of 25% due to increased air conditioning loads when the car is turned on [21,22]. A viable solution is a PV equipped parking lot, which provides sun shade and additional protection from inclement weather for the vehicles charging underneath them. ...
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Electrification of transport and the deployment of plug‐in electric vehicles (PEVs) shift emissions from tail‐pipes to bulk power systems (BPSs). Coordinated distributed energy resources and PEV charging can mitigate the impact of this shift. This study presents an analysis of photovoltaic (PV) solar parking lots that address this benefit. Real‐world charging data, solar data, and electricity tariffs are used to determine the microgrid system that minimises the cost of retrofitting an existing parking lot with PV and PEV infrastructure coupled. The result is a load scheduling algorithm that takes into account tariffs and insolation to reduce costs while ensuring customer satisfaction. The techno‐economic feasibility of PV infrastructure in the microgrid is determined by minimising the net present cost (NPC) in two case studies: Victoria, BC, and Los Angeles, CA. Relatively low solar irradiation and electricity prices make it economically infeasible to install solar panels in Victoria even though the operational costs are reduced by 11%. In Los Angeles, high time‐of‐use prices, together with abundant solar radiation, make PV retrofitting economically feasible with any array capacity. At the current solar infrastructure price, coordinated charging in this region yields 8–16% savings on NPC and smaller feeder size requirements with greater load growth opportunities.
... Experiments at Ford Motor Company showed that improving driving behaviour can improve fuel economy by an average of 24% (Berry 2010). Opening windows in summer makes a vehicle to be less aerodynamic, thereby increasing fuel consumption (Huff et al. 2013). ...
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The automotive industry is growing faster than any other industry and neck on neck with this growth is the demand for lightweight components. This is a pull factor, which is primarily influenced by the drive towards reducing fuel consumption and emissions to the atmosphere. The stakes are very high in the quest to satisfy the insatiable customer hunger for reduced fuel consumption. Stringent emission regulations have also been put in place in order to mitigate the adverse effects of global warming. This has placed tremendous pressure for an increased production of light vehicle components. Hence the lighter the better, and this paper focuses on the lightweighting technologies that are being implemented in the automotive industry, and how weight reduction is vital in reducing vehicle fuel consumption and global warming. Two weight reduction methods, material substitution and topology optimization are reviewed and analyzed based on cost, strength and stiffness. The paper also discusses the contribution that vehicle mass has on the driving cycle when compared to other parameters that affect fuel consumption.
... A relevant loss was observed both for the battery SoC value and the residual driving range at the end of the driving missions. For this reason, an immediate solution could be to not activate the air conditioning system [41] when driving in urban environments and/or for short trips; on the other hand, BEV performance losses must be accepted for cold and hot ambient temperatures due to the activation of the entire HVAC system. ...
Article
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Sustainable mobility has recently become a priority of research for on-road vehicles. Shifting towards vehicle electrification is one of the most promising solutions concerning the reduction in pollutant emissions and greenhouse gases, especially for urban areas. Nevertheless, battery electric vehicles might carry substantial limitations compared with other technologies. Specifically, the electric range could be highly affected by the ageing process, non-optimal thermal management of the battery and cabin conditioning. In this paper, a model for the estimation of the residual range of electric vehicles is proposed accounting for the influence of battery state of health, battery pack temperature, power consumption of the main vehicle auxiliaries, and battery pre-heating on the residual driving range. The results of the model application to an L7 battery electric vehicle highlighted that the electric range can be highly affected by several factors related to real-world driving conditions and can consistently differ from nominal values.
... However, as long as the AC system works with a vapor compression system, it will reduce the engine power to drive the compressor which increases fuel consumption and exhaust emissions [14][15][16][17][18]. Meanwhile, the massive use of conventional fuels such as gasoline and diesel have become the attention of researchers in the last few decades because they increase the greenhouse gas effect. ...
Article
This study reports an experimental investigation of cooling power harvesting in LPG-fueled vehicles. The heat of vaporization for LPG in the vaporizer which is initially transferred from the engine coolant is modified by circulating low-temperature water by adding a chiller which placed on a three-passenger pick-up car. Low-temperature water is circulated from the chiller to the vaporizer and back to the chiller by a pump to transfer the cooling power. Meanwhile, the air from the cabin is flowed by an electric blower across the chiller and back to the cabin to transfer heat to the water loop in the chiller. The test was carried out on Daihatsu 1945 cm³ at 1000, 2000, and 3000 rpm, where LPG consumption followed the engine load and obtained LPG mass flow rates of 0.022, 0.236, and 0.350 g⋅s⁻¹. With this vaporizer-chiller combination, the average cooling power of 41.51, 52.05, 110.29 W is obtained at 1000, 2000, and 3000 rpm, respectively. With an average cooling power of 124.5 W at 3000 rpm, it was proven to compensate for the thermal load in the cabin by 15.312, 11.67, and 80.31 kJ at 100, 2000, and 3000 rpm for 60 minutes of testing. This method can be applied as a secondary AC system to improve the performance of the main AC system in a vehicle. The actual cooling power from the LPG to the water loop can be increased by modifying the heat transfer contact area in the vaporizer cavity or by applying a high-efficiency vaporizer.
... One of it is using of air conditioning system AC. Under very high temperature, using of air condition system can increase the fuel consumption of a conventional vehicle's by more than 25%, particularly on short trips [1,2,3]. The effect of air conditioning system in case of hybrids, plug-in hybrids, and electric vehicles (EVs) can be higher on a percentage basis [2]. ...
... This paper documents a study aimed specifically at the effects of common vehicle in-use alterations or modifications such as trailer towing, use of rooftop cargo boxes versus hitch-mounted cargo trays, low tire pressure, and open windows. Previous studies have detailed the impact of intake air filters, highway cruise speed, and air conditioning on fuel economy of light-duty vehicles [1,2,3,4]. ...
Article
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In this paper, an experimental study of an auto-controlled mobile air conditioning (MAC) system with an externally-controlled variable displacement compressor (EVDC) is performed and analyzed. A new displacement control method of EVDC is developed concerning about evaporator characteristics and in-car temperature fluctuation, which indicate the quality of the MAC system. Based on occupant’s thermal comfort, the wind-tunnel test results show that the MAC system with an EVDC can maintain the deviation of in-car temperature no more than 2 °C compared with the occupants’ desired one. This MAC system gives the occupants a good thermal comfort sensation in the rapid changing environment. The comparison shows that the discharge pressure changes of EVDC vary faster than that of the fixed displacement compressor, which reflects the effect of the internal climate changes.
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How much fuel does vehicle air conditioning actually use? This study attempts to answer that question to determine the national and state-by-state fuel use impact seen by using air conditioning in light duty gasoline vehicles. The study used data from US cities, representative of averages over the past 30 years, 1X—see Definitions, the Toyota Prius, the Honda Insight, a 3X Hybrid, and a Fuel Cell Hybrid) with a varying auxiliary load. For a conventional 1X vehicle, using the AC increases fuel consumption by 35% (or drops fuel economy by 26%). For the Honda Insight, using the AC increases fuel consumption 46%. For a 3X Hybrid, using the AC increases fuel consumption 128%. whose temperature, incident radiation, and humidity varied through time of day and day of year. National surveys estimated when people drive their vehicles during the day and throughout the year. A simple thermal comfort model based on Fanger's heat balance equations determined the percentage of time that a driver would use the air conditioning based on the premise that if a person were dissatisfied with the thermal environment, they would turn on the air conditioning. Vehicle simulations for typical US cars and trucks determined the fuel economy reduction seen with AC use. Combining these statistics and models with vehicle and truck registrations and vehicle miles traveled Figure 1: Percent Vehicle Energy Uses/Losses in a Conventional 27-mpg (8.7-l/100km) Vehicle resulted in a state-by-state estimate of fuel used for air 100 conditioning in vehicles. The study showed that the US uses 7.1 billion gallons (27 billion liters) of gasoline every year for air conditioning vehicles, equivalent to 6% of domestic petroleum consumption, or 10% of US imported crude oil.
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The energy used to air condition an automobile has a significant effect on vehicle fuel economy and tailpipe emissions. If a small reduction in energy use can be applied to many vehicles, the impact on national fuel consumption could be significant. The SCO3 is a new emissions test conducted with the air conditioner (A/C) operating that is part of the Supplemental Federal Test Procedure (SFTP). With the 100% phase-in of the SFTP in 2004 for passenger cars and light light-duty trucks, there is additional motivation to reduce the size of the A/C system. The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) is investigating ways to reduce the amount of energy consumed for automobile climate control. If the peak soak temperature in an automobile can be reduced, the power consumed by the air conditioner may be decreased while passenger comfort is maintained or enhanced. Solar reflective glass is one way to reduce the peak soak temperature. NREL and PPG Industries conducted a test program with Sungate laminated solar reflective glass installed in a Ford Explorer to quantify improvements in fuel economy and reductions in tailpipe emissions. Test results showed a dramatic reduction in interior and glass temperatures. After the A/C system and its effect on the passenger compartment were modeled to assess the potential reduction in compressor power, the vehicle performance was predicted.
Final Regulations for Revisions to the Federal Test Procedure for Emissions From Motor Vehicles
Federal Register, Vol. 61, No. 205, October 22, 1996, "Final Regulations for Revisions to the Federal Test Procedure for Emissions From Motor Vehicles," Final Rulemaking.
2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas Emissions and Corporate Average Fuel Economy Standards
Federal Register, Vol. 77, No. 199, October 15, 2012, "2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas Emissions and Corporate Average Fuel Economy Standards," Final Rule.
Design and Analysis of a Thermoelectric HVAC System for Passenger THIS DOCUMENT IS PROTECTED BY U.S. AND INTERNATIONAL COPYRIGHT. It may not be reproduced, stored in a retrieval system, distributed or transmitted, in whole or in part, in any form or by any means
  • D Wang
  • D Crane
  • J Lagrandeur
Wang, D., Crane, D., and LaGrandeur, J., "Design and Analysis of a Thermoelectric HVAC System for Passenger THIS DOCUMENT IS PROTECTED BY U.S. AND INTERNATIONAL COPYRIGHT. It may not be reproduced, stored in a retrieval system, distributed or transmitted, in whole or in part, in any form or by any means. Downloaded from SAE International by Shean Huff, Thursday, March 21, 2013 12:46:29 PM Vehicles," SAE Technical Paper 2010-01-0807, 2010, doi: 10.4271/2010-01-0807.