CC BY
104
Section 11. Transport
DOI: http://dx.doi.org/10.20534/ESR-16-9.10-234-236
Mukhitdinov Akmal Anvarovich, Tahskent institute of design, construction and maintenance of automotive roads, professor Head of chair "Information systems of management on transport" E-mail: [email protected] Ziyaev Kamoliddin Zukhritdinovich, Tahskent institute of design, construction and maintenance of automotive roads, scientific researcher E-mail: [email protected]
Method for evaluating the energy efficiency of regulated driving cycles
Abstract: The thoretical fundamentals of defining the energy consumption of a car under urban conditions and method for evaluating the energy efficiency of vehicles and driving cycles are represented in this paper.
Keywords: Energy, driving cycle, average speed, energy efficiency, car.
Since the usage of natural resources has been increasing in all branches the energy efficiency and energy saving are significant directions for economical development. Nowadays there are the number of models and modifications of cars more than 3000 in the world. Production volume of them more than 75% of total volume 89,7 million including trucks and buses [5]. The share of cars in consumption of oil products is 67% [6]. Mainly most cars are used in cities.
The traffic jam, frequent stops, decreasing of average speed, increasing of uneven ride — acceleration and deceleration are occurred in urban conditions.
The fuel consumption in urban conditions and on the high way is more applied gauge of fuel economy of vehicles in practice. Corresponding city and high way driving cycles are developed for evaluating the fuel consumption of each type of the vehicle in mentioned conditions [1, 8-11].
There are own regulated driving cycles in different countries, with the help of which fuel economy and emission of vehicles are determined and more than 55 of them (for instance LA 92, Unified LA 92, Japanese 10-15, CBD, SAE J1376, ECE+EUDC, HWFET, UDDS, ECE, EUDC, NYCC, UDDS, US06 and etc.) are analyzed.
After analyzing more than 55 driving cycles was fixed, that duration of operation of the vehicle at unstable regimes in urban conditions reaches up 67%. A distance of acceleration and deceleration sections, which essentially influence to average speed, is about 70-80% of total distance, covered by a vehicle [3, 75-87].
The average speed and ride regime of cars in urban conditions is the one of performances, which defines energy efficiency of a car. Changing the average speed of the vehicle due to outer factors influences to its energy efficiency.
The average speed change of the vehicle in Tashkent city depending on day times, week days and seasons of the year, is determined by experiment and we can see the following results. The range of average speed change in day times is from 29.53 km/h (11-12 a. m.) to 26.67 km/h (7-8 p. m.), i. e. increasing is 5.73% dET = NT ■ dta; (3)
and decreasing is 4.50% with reference to fixed average speed dET = m 5 ■ v ■dv + (N + Nf) ■dt ; (4)
(27.94 km/h). The range of average speed change in week days is from 28.26 km/h (on Fridays) to 27.53 km/h (on Thursdays), i. e. increasing is 1.14% and decreasing is 1.46% with reference to fixed average speed. The range of average speed change in seasons of the year is from 28.56 km/h (in summer) to 25.10 km/h (in winter), i. e. increasing is 2.22% and decreasing is 10.14% with reference to fixed average speed.
It is possible to improve the fuel economy and emission parameters of the vehicle through defining the energy efficiency of driving cycles, share of average speed change, mentioned above and monitoring the change of energy efficiency. It increases the importance of developing driving cycles for certain conditions and evaluating the energy efficiency of latter.
Nowadays there is no method for comparative evaluation of standardized driving cycles and all standardized driving cycles have different parameters. As the driving cycle is the one of definers of energy consumption of the vehicle, the energy, consumed per distance (or time) can be applied as criterion for comparative evaluation [2, 124-135]. Defining the energy balance of the vehicle in moving phase of driving cycle is necessary to reach the goal mentioned above. The first stage to make the energy balance of the vehicle is to make force and power balances at three main phases of the vehicle ride:
Acceleration phase. The power balance of the vehicle looks as following:
dv
■ v--^ + (P + Pf ) • v ;
NT = ma
dt
NT • dty = ma •Sr • va • dva + (Na + Nf) • dta
Where, NT — Traction power, (Wt); Nf — rolling resistance power, (Wt); Na — air resistance power, (Wt); ta — acceleration time, (s); va — vehicle speed, (m/s).
dET = NT ■ dta;
dET = ma -Sr ■ va ■ dva + (Na + Nf) -dta;
(1) (2)
Method for evaluating the energy efficiency of regulated driving cycles
Where Ea — energy, required for accelerating a vehicle, (J);
By integrating both sides of equation (2) we can get following
2 2 t
ET = ma-5r • vf—— + j(Na + Nf)• dta =;
" " 2 0 " " (5)
vf 2 - v.2
= ma -5r ■ —-— + j va • (fr ■ (1 + af ■ va2) • ma ■ g + ce ■ va2) • dta
2 0
dva ( dva
Taking an acceleration ofthe vehicle as constant a = ~Ti I dta =—5
dt I a
a
and integrating the equation (4) relatively va,
- +
vf - vi E = m -5 '
2
+v{va-( fr-(1 + af - va 2)-ma - g + cae - va2)-dva ' V a
(6)
Then the energy, required to accelerate the vehicle from initial speed v. to final speed vf for time ta is
vf -
vf -
Ea = ma -Sr ■—-— + ma ■ g ■ f
a a r 2 a r 2 ■a
+ (Cae + ma ' g ■ fr ' af ) ' (Vf ' - V,
4 ■a
(7)
Stable ride phase. Required energy for stable ride is defined as the sum of energies consumed for rolling resistance force and air drug.
Es = (va ■ fr • (1 + af ■ va2)■ ma ■ g + cae ■ vj)-t, ; [ J ] (8)
Where Es — energy, required for stable ride, (J);
va — speed of the vehicle at stable ride, (m/s);
ts — ride time at speed va, (s).
Deceleration phase. Deceleration of the vehicle occurs by energy distributing (which is equal to the sum of kinetic energy of the vehicle and energy of its rolling parts) which is usually absorbed by brakes of the vehicle.
2 2
Ed = m A • —f ; [J] (9)
Taking in account mentioned above equations the energy balance of the vehicle in driving cycle can be determined as following.
Edc = Ea + Es + Bd ; [kJ] (10)
Defining the ratio of amount energy, consumed for driving cycle to covered road is necessary to define the specific energy per road unit.
Ef = Ed ; [kJ/m] (11)
The energy efficient driving cycle can be determined by comparing the standardized driving cycles between and using specific energy for certain vehicle model.
Fig.1. Regulated driving cycle Eudc Fig.2. Regulated driving cycle Eudc_Low
The parameters of driving cycles EUDC (Fig.1) and EUDC_LOW (Fig.2) are analyzed with the help of mentioned above method and energy consumption is determined (Table 1.).
Table 1.
Name of cycle Time, s Road, km Average acceleration/deceleration m/s 2 Max. speed, m/s Average speed, m/s Energy, kJ Energy per road unit kJ/m
EUDC 400 6915 0.38/0.93 33.1 17,3 7100.4 1.03
EUDC LOW 400 6610 0.42/1.0 25.0 16.5 6329.8 0.96
In order to define the energy economy of mentioned driving
cycles the specific energy is determined
E 7100.4 , _ J- = 1.03 kJ/m
-'ef (EUDC )
"V(EUDC LOW)
dc_
S
6915 6329.8
= =-= 0.96 kJ/m
S 6610
The results show that the driving cycle EUD C_LOW is energy efficient. But it is not correct to evaluate a difficulty level of driving cycle by energy with the help of mentioned method. Increasing the share of unstable ride of the vehicle causes decreasing the energy efficiency of last. It raises the significance of evaluating a difficulty level of certain driving cycles.
A difficulty level of driving cycle can be defined through energy, consumed to cover the distance of driving cycle with constant average speed of driving cycle on plain road. The energy consump-
tion, defined by second method is the minimal consumption of the energy to cover the certain distance and it increases by changing the ride regimes. Hence, it is possible to evaluate a difficulty level of driving cycles by comparing defined energy consumptions.
It is obviously that increasing the share of unstable ride regimes of driving cycles, causes raising a difficulty level of latter, i. e. energy consumption will increase. Therefore coefficient Y is applied as criterion for evaluating driving cycles.
A difficulty level of driving cycles by energy efficiency can be determined with the help of following equation:
- Ejk.
Y =
Vca
Where: Edc - energy consumption of driving cycle, (kWt);
EVa - energy, consumed to cover the distance of driving cycle with constant average speed of the cycle.
Figure 3. Changing the energy efficiency of vehicles Nexia SOHC ва Nexia DOHC depending on driving cycles
Difficulty levels of a few driving cycles (ECE, IM240, EUDC_ LOW, EUDC, ARTERIAL) for two models of the vehicle NEXIA, were defined with the help of the method mentioned above (Fig. 3).
Hence, we can see that Nexia DOHC has high energy efficiency than Nexia SOHC in ECE driving cycle [4, 93-94]. In fact the fuel consumption of the Nexia DOHC more than Nexia SOHC but energy usage efficiency of the first is high. The energy efficiency of both vehicles is the same in EUDC LOW and ARTERIAL driving cycles. Driving cycle IM240 is most difficult and driving cycle
EUDC_LOW is easier for mentioned vehicles by energy efficiency than others.
This method allows choosing optimal type of a vehicle for urban conditions or choosing optimal driving cycle for certain vehicle by energy usage efficiency.
The conclusion is that nowadays with the help of applied complex and continuously monitoring system of transport it is possible to define and evaluate the energy efficiency of vehicles all time.
References:
1. Антипов С. И., Дементьев Ю. В. "Современные испытательные ездовые циклы и их актуальность при создании алгоритма работы системы управления автомобиля с КЭУ", Известия Волгоградского государственного технического университета, - 2013. - № 10 (113)/том 6. C. 8-11.
2. Гудцов В. Н., Современный легковой автомобиль. Экология. Экономичность. Электроника. Эргономика. - Кнорус, - 2015. -449 с.
3. Кушвид Р. П., Испытания автомобиля, - М.: Москва, - 2011. - 380 с.
4. Правила ЕЭК ООН N 83 «Единообразные предписания, касающиеся официального утверждения транспортных средств в отношении выбросов загрязняющих веществ в зависимости от топлива, необходимого для двигателей».
5. URL: http://www.oica.net/category/production-statistics/2014-statistics
6. URL: http://www.nationmaster.com
DOI: http://dx.doi.org/10.20534/ESR-16-9.10-234-236
Shermukhamedov Abdulaziz Adilkhakovich, Tashkent Automobile and Road Institute, professor, Head of Department of Reliability of Land Transport Systems
E-mail: [email protected]
Baboev Alijon Madaminovich, Tashkent Automobile and Road Institute, senior staff scientist-applicant of Department of Reliability of Land Transport Systems
Design procedure of the mode of movement of the articulated lorry transporting liquid cargo in mountain conditions
Abstract: The mathematical model and design procedure of a motion mode (regime) of the semi-trailer truck transporting liquid cargo is proposed. The model allows to define average speed of the semi-trailer truck taking into account change of motion parameters (turn radius, speed, acceleration, up- or down-hilling, influence of dynamics of a liquid cargo on tank walls).
