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Section 4. Machinery construction
Marchenko Andrii Petrovych, Doctor of Technical Science, Professor, Deputy Head of the Department of internal combustion engines of the National Technical University "Kharkiv Polytechnic Institute", Kharkiv, Ukraine,
Ali Adel Hamzah,
graduate student of Department of internal combustion engines of the National Technical University ".Kharkiv Polytechnic Institute",
Kharkiv, Ukraine, Omar Adel Hamzah, graduate student of Department of internal combustion engines of the National Technical University
".Kharkiv Polytechnic Institute", Kharkiv, Ukraine, E-mail: [email protected]
Parameter optimization of heat recovery steam generation for hyndai engine H25/33
Abstract: Conducted experimental studies of thermodynamic parameters changes in working environments in Hyundai engine H25/33 when the engine is operating at different times of the year. Obtained regressional dependence to calculate the parameters of working environment in the range of ambient temperature changes from 0 to 40 °C. Based the possibility of use of ICE cooling water in the heat recovery steam generator in its appropriate treatment. Formed mathematical model of the heat recovery steam generator for Hyundai engine H25/33 and made its numerical implementation. As a result of numerical implementation of mathematical models of heat recovery steam generator the optimal parameters of the generated steam while using waste-gas heat and partially cooling water heat in Hyundai engine H25/33.
Keywords: Heat recovery, diesel engines, exhausts gas, Renewable energy, heat power, waste heat generator
Introduction and statement of the problem. the internal combustion engine makes inefficient the uti-
About 60% of the heat produced in the cylinders lization plants in which working medium is water. of internal combustion engines is lost irretrievably into Hyundai engine H25/33 refers to the internal-com-
the environment. This leads to the need to: further im- bustion engine with a turbocharger. Distinctive feature
prove the efficiency of the internal combustion engine, of the internal-combustion engine with turbocharge is
expansion of areas of use and increasing the amount of a high excess air ratio (a « 3). This explains the signifi-
energy generated by them [1-2]. One of the most prom- cant change in the exhaust gas temperature at the time
ising ways of solving these problems is the utilization of of purging of the engine cylinder [7]. This calls for an
heat irretrievably lost in the environment [3-5]. experimental study of the exhaust gas parameters in the
To date worked out technical solutions in using the existing diesel generator on the basis of Hyundai engine
heat of exhaust gases of main marine power systems H25/33.
(mainly marine internal-combustion engine) for receiv- Another significant feature of the high values of the
ing of aqueous vapor in the waste heat recovery boiler. coefficient of excess air in the Hyundai engine H25/33 is
In future, with this aqueous vapor: is heated fuel (heavy relatively low absolute moisture content of the flue gases
fuel oil-fuel for the main engine), or is used for energy due to the high dilution of the mentioned with ambi-
production based on Rankine cycle [6]. Other second- ent air. Due to the nature of climatic conditions at the
ary heat source (water-cooling system of internal-com- location of power electric plant with Hyundai engine
bustion engine) is used loosely. This is due to the fact H25/33 the absolute moisture content of the air varies
that the low thermal capacity in the cooling system of greatly by season. That in turn has a significant impact
on the parameters of exhaust gases after Hyundai engine H25/33.
The aforementioned features of Hyundai engine H25/33 in the formation of flue gas heat recovery systems require: experimental studies of parameters of working environments at different climatic conditions; forming of a mathematical model of heat recovery steam generator, which takes into account changes in the parameters of the working media depending on the climatic conditions of power electric plant location; numerical implementation of the developed mathematical model of heat recovery steam generator to determine the optimal technical parameters of the generated steam.
Mathematical model of heat recovery steam generator that uses the water from the internal combustion engine cooling system.
Mathematical model of heat recovery steam generator is based on the recommendations for the design
of ship recycling steam generators [8] and a standard method of calculation of steam boilers [9-11].
In addition, in mathematical model is taken into account: dependences of the actual parameters of the working environment in Hyundai engine H25/33 from the environmental parameters: gas temperature at the outlet of the engine after turbocharger; temperature of water at the outlet of the radiator and temperature of water at the outlet of air cooler; effect of the composition of the fuel (fuel oil Crude oil Heavy fuel oil) on the thermal characteristics of the waste gases; dependence of the absolute moisture content of the waste gases from the excess air ratio in the Hyundai engine H25/33; use of appropriately treated water cooling system Hyundai engine H25/33, etc.
Parametric variation of the exhaust gases, water and steam in the steam generator can be represented by the circuit shown in Fig. 1.
Fig.1. Pattern of variation of parameters in flue gas parameters from ICE, water and steam in the heat recovery steam generator
As input parameters for the calculation of heat recovery steam generator can be taken: i0 = f (p0) - steam enthalpy in the drum separator (is determined by the pressure of the cooling system condensing of Hyundai H25/33, supplied to the heat recovery steam generator), kJ/kg; i4 = f (p0,t 4) - condensate enthalpy supplied from the cooling system of Hyundai H25/33 (depending on the pressure and temperature of the condensate before economizer); kJ/kg; Gg - flue gas flow, kg/s; Igx - enthalpy of flue gas. kJ/kg; I - enthalpy of ambient air, kJ/kg; p0 - pressure in the condensate supply system of the engine cooling system, bar; t - condensation tem-
perature of the engine cooling system before the economizer, oc.
Parameter values Ig 1, Iair, p0 and t4-kg (are determined on the basis of experimental studies of the parameters of the working environment in Hyundai engine H25/33).
For each of the convective heating surfaces (super heater, evaporator and economizer-fig 1) can be formed the differential energy equation from the exhaust gases and the production environment. Changing the amount of heat in a heat exchanger element of length dx given away by gases and perceived by the working environ-
ment, equal to the amount ofheat transferred by the heat transfer. Assuming, that in the heat recovery steam generator there are no additional heat sources (absent radiant heat from the internal combustion engine cylinder) and it is gasproof (absent airflow from the environment) the system of differential equations for the flue gas system and the operating environment can be written as:
-V-Gg■ dig = K. ■ (Tg-tj)■F■dx.
-Gp■ di = K. ■(T' -t )dx x
(1)
where Gg - design flow of exhaust gas, kg/s; Gp - flow of working medium (steam, water), kg/s: p - heat preservation rate; Ig - enthalpy of the gas, referred to 1 kg of flue gas, kJ/kg; i - enthalpy of the working fluid (steam, water), kJ/kg; K. - current value of the heat transfer coefficient, bt-m-2-k-1; Tg-t - current value of the temperature difference between flue gases and the working environment, °C; F/x -relation of surface-to-length of the device, m; x-current value of the length of the heat exchanger for exhaust gases while moving, m.
Numerical implementation of mathematical modeling of heat recovery steam generator for Hyundai engine H25/33
Results of computer simulation in the steam generation in the heat recovery steam generator provided by approximation of the exhaust gas temperature to the inlet water temperature in the economizer show that, depending on the ambient temperature in the steam is generated from 1400 to 1500 kg of steam/h.
According to Newton — Richman's equation for convective heat transfer in surface devices to achieve the maximum degree of superheated vapor temperature ap-
proaches of the superheater outlet to the temperature of exhaust gases entering the heat recovery steam generator must be done one of the following conditions: heat transfer coefficient Kj - ro - or heat exchange surface Fj - ro.
These conditions require an analytical assessment of the real values of the coefficient of heat transfer Kj and heat exchange surface Fj in the apparatus of heat recovery steam generator, since according to the Newton — Rich-man's equation for convective heat transfer in surface devices at a value Atmax ^ 0 heat exchange surface Fj -ro. And it is impossible to achieve in real heat exchangers at Kj= const.
Boundary temperature difference ATkp at which occurs a sharp increase in the heat transfer surface is defined as follows:
f1(AT '=dk Fee(AT ^2.414-AT-0.036-AT2 -40.432 (2) root (((AT), AT) ,oC. ATkp = 32.527
According to the analysis performed was received critical ATkp = 32.527 °C. By reducing this value, there is a sharp increase in the required heating surface in steam superheater.
As is the case with the steam superheater in the economizer is impossible to achieve the flue gas temperature at the outlet of the economizer equal to the inlet water temperature in the economizer. According to the analysis performed is received critical value ATke = 32.527°C. By reducing this value, there is a significant increase in the required heating surface in the economizer.
On the basis of thermodynamic analysis of work of heat recovery steam generator are received thermodynamic efficiency nuk and energetic efficiency neuk
(Fig. 1).
Ggp
1.5x10" 484x10" .468x103 452x10" .436x103 1.42x103
390 380 TgP
-
- 370 360
16
24
32
40
1
0.98 0.96 0.94 0.92
nuke
a) 6)
Fig.1 Linear connection of thermodynamic efficiency (nuk) and energetic efficiency (neuk) of heat recovery steam generator (a), mount of the generated superheated steam (Ggp) and overheating temperature (Tgp)
(6) from ambient temperature (ta).
Besides found dependencies tfuk = f(ta) and recovery steam generator. Fig. 1 shows the dependence
neuk = f (ta) an important parameter for the thermo- of the amount of generated steam Ggp and superheated
dynamic analysis of the Rankine cycle are the param- steam Tgp from ambient temperature ta. eters of the superheated steam at the outlet of the heat
Received data on the number of generated steam (Ggp) and superheated steam temperature (Tgp) will continue to be used in determining the thermodynamic characteristics of the steam turbine Conclusions.
Numerical implementation of mathematical modeling of heat recovery steam generator for Hyundai engine H25/33 power electric plant, located in the climatic zone of Iraq, showed:
1. Minor dependence of the thermodynamic characteristics of the heat recovery steam generator to the
ambient temperature.
In the zone of optimal parameters of the generated steam thermodynamic efficiency varies between 0.8015 ...0.8040 when the ambient temperature is from 0 to 40 °C.
2. Amount of steam generated more significantly depends on the ambient temperature. When ambient temperature changes from 0 to 40 °C the optimum amount of steam generated increases from 1440 to 1500 kg/h. And the optimum temperature of the superheated steam is increased from 365 to 387 °C.
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