| 1. |
- Binder, Christian, 1988-, et al.
(författare)
-
Comparison of heat losses at the impingement point and in between two impingement points in a diesel engine using phosphor thermometry
- 2019
-
Ingår i: 2019 JSAE/SAE Powertrains, Fuels and Lubricants. - Kyoto, Japan : SAE International. - 0148-7191.
-
Konferensbidrag (refereegranskat)abstract
- In-cylinder heat losses in diesel engines reduce engine efficiency significantly and account for a considerable amount of injected fuel energy. A great part of the heat losses during diesel combustion presumably arises from the impingement of the flame. The present study compares the heat losses at the point where the flame impinges onto the piston bowl wall and the heat losses between two impingement points. Measurements were performed in a full metal heavy-duty diesel engine with a small optical access through a removed exhaust valve. The surface temperature at the impingement point of the combusting diesel spray and at a point in between two impingement points was determined using phosphor thermometry. The dynamic heat fluxes and the heat transfer coefficients which result from the surface temperature measurements are estimated. Simultaneous cylinder pressure measurements and high-speed videos are associated to individual surface temperature measurements. Thus each surface temperature measurement is linked to a specific impingement and combustion events. An analysis of the surface temperature in connection with the high speed images reveals the great impact of flame impingement on instantaneous local heat flux at the impingement point. Absence of such an effect in between two impingement points implies an inhomogeneous temperature field.
|
|
| 2. |
- Binder, Christian, 1988-, et al.
(författare)
-
Experimental Determination of the Heat Transfer Coefficient in Piston Cooling Galleries
- 2018
-
Ingår i: SAE Technical Papers. - Heidelberg, Germanay : SAE International. - 0148-7191.
-
Tidskriftsartikel (refereegranskat)abstract
- Piston cooling galleries are critical for the pistons’ capability to handle increasing power density while maintaining the same level of durability. However, piston cooling also accounts for a considerable amount of heat rejection and parasitic losses. Knowing the distribution of the heat transfer coefficient (HTC) inside the cooling gallery could enable new designs which ensure effective cooling of areas decisive for durability while minimizing parasitic losses and overall heat rejection. In this study, an inverse heat transfer method is presented to determine the spatial HTC distribution inside the cooling gallery based on surface temperature measurements with an infrared (IR) camera. The method utilizes a piston specially machined so it only has a thin sheet of material of a known thickness left between the cooling gallery and the piston bowl. The piston - initially at room temperature - is heated up with warm oil injected into the cooling gallery. The transient of the piston’s outer surface temperature is captured with an IR camera from the top. Combining the temperature transient of each pixel, the HTC is later obtained through an inverse heat transfer solver based on one-dimensional heat conduction inside the piston material. To the authors’ knowledge, the current study presents the first application of an inverse heat transfer method for spatially resolved and experimentally determined heat transfer coefficients inside a piston cooling gallery. Preliminary measurements at standstill to demonstrate the method display an area of increased heat transfer where the entering oil jet impinges onto the wall of the cooling gallery.
|
|
| 3. |
- Binder, Christian, 1988-
(författare)
-
Experiments on Heat Transfer During Diesel Combustion Using Optical Methods
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Transportation is a crucial part of modern societies. This includes their economies. Trade and the transportation of goods have a great influence on prosperity. Nevertheless, the transportation sector with road transport in particular is heavily dependent on fossil fuels and emits a significant amount of greenhouse gases. One approach to mitigate the negative environmental impact of road transport is to increase the efficiency of its most common propulsion system, that is the internal combustion engine. Due to its dominant role in the road freight transportation sector, this thesis directs its attention to heavy-duty diesel engines. In-cylinder heat losses are one of the main factors that reduce engine efficiency. Therefore, the objective of this thesis is to gain a better understanding of the processes that influence in-cylinder heat losses by resolving them in time and space using optical methods. In diesel engines, most of the in-cylinder heat losses are transferred to the piston. As a result, this thesis focuses specifically on that component.In this research project, the task to determine in-cylinder heat losses to the piston in heavy-duty diesel engines is divided into two parts. The most important part consists of fast surface temperature measurements on the piston using phosphor thermometry. The heat transfer coefficient inside the piston cooling gallery defines an additional steady-state boundary condition.The work presented in this thesis includes therefore efforts to improve in-cylinder surface temperature measurements and an assessment of their accuracy and precision. Furthermore, it comprises of experimental results from measurements on steel pistons and a piston with an insulating thermal barrier coating. Results reveal spatial differences of the heat transfer during diesel combustion. Measurements at the impingement point indicate a strong influence of flame impingement on local heat transfer. A correlation is detected between heat transfer and cycle-to-cycle variations of flame impingement.The thesis also reports efforts to determine the heat transfer coefficient inside the piston cooling gallery. Using an infrared camera a method is presented to spatially resolve convective heat transfer inside this cooling channel.
|
|
| 4. |
- Binder, Christian, 1988-, et al.
(författare)
-
Heat Loss Analysis of a Steel Piston and a YSZ Coated Piston in a Heavy-Duty Diesel Engine Using Phosphor Thermometry Measurements
- 2017
-
Ingår i: SAE International Journal of Engines. - : SAE International. - 1946-3936 .- 1946-3944. ; 10:4, s. 1954-1968
-
Tidskriftsartikel (refereegranskat)abstract
- Diesel engine manufacturers strive towards further efficiency improvements. Thus, reducing in-cylinder heat losses is becoming increasingly important. Understanding how location, thermal insulation, and engine operating conditions affect the heattransfer to the combustion chamber walls is fundamental for the future reduction of in-cylinder heat losses. This study investigates the effect of a 1mm-thick plasma-sprayed yttria-stabilized zirconia (YSZ) coating on a piston. Such a coated piston and a similar steel piston are compared to each other based on experimental data for the heat release, the heat transfer rate to the oil in the piston cooling gallery, the local instantaneous surface temperature, and the local instantaneous surface heat flux. The surface temperature was measured for different crank angle positions using phosphor thermometry. The fuel was chosen to be n-heptane to facilitate surface temperature measurements during non-skip-fire, thermally stabilized operating conditions. Assuming one-dimensional heat transfer inside each piston, the local instantaneous surface heat flux was calculated using the heat transfer rate to the oil in the piston cooling gallery and the surface temperature measurements. The results from this study show that the surface temperature variation is similar for both pistons. The instantaneous heat flux during combustion is however significantly greater for the steel piston than the coated piston. The heat release analysis also indicates that combustion is slower for the piston with the yttria-stabilized zirconia coating.
|
|
| 5. |
- Binder, Christian, 1988-, et al.
(författare)
-
Phosphor Thermometry for In-Cylinder Surface Temperature Measurements in Diesel Engines
- 2019
-
Ingår i: Measurement science and technology. - 0957-0233 .- 1361-6501.
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Surface temperature measurements in technically relevant applications can be very hallenging and yet of great importance. Phosphor thermometry is a temperature measurement technique that has previously been employed in technically relevant applications to obtain surface temperature. The technique is based on temperature-dependent changes in a phosphor’s luminescence. To improve the accuracy and precision of temperature measurements with this technique, the present study considers, by way of example, the impact of conditions inside the cylinder of a diesel engine on decay time based phosphor thermometry. After an initial, general assessment of the effect of prevailing measurement conditions, this research investigates errors caused by soot luminosity, extinction, signal trapping and changes of phosphors’ luminescence properties due to exposure to the harsh environment. Furthermore, preferable properties of phosphors which are suitable for in-cylinder temperature measurements are discussed. 16 phosphors are evaluated, including four which – to the authors’ knowledge –have previously not been used in thermometry. Results indicate that errors due to photocathode bleaching, extinction, signal trapping and changes of luminescence properties may cause an erroneous temperature evaluation with temperature errors in the order of serval tens of Kelvin.
|
|
| 6. |
- Binder, Christian, 1988-, et al.
(författare)
-
Study on heat losses during flame impingement in a diesel engine using phosphor thermometry surface temperature measurements
- 2019
-
Ingår i: SAE Technical Papers. - Detroit, United States : SAE International. - 0148-7191.
-
Tidskriftsartikel (refereegranskat)abstract
- In-cylinder heat losses in diesel engines decrease engine efficiency significantly and account for approximately 14-19% [1, 2, 3] of the injected fuel energy. A great part of the heat losses during diesel combustion presumably arises from the flame impingement onto the piston. Therefore, the present study investigates the heat losses during flame impingement onto the piston bowl wall experimentally. The measurements were performed on a full metal heavy-duty diesel engine with a small optical access through a removed exhaust valve. The surface temperature at the impingement point of the flame was determined by evaluating a phosphor's temperature dependent emission decay. Simultaneous cylinder pressure measurements and high-speed videos are associated to the surface temperature measurements in each cycle. Thus, surface temperature readings could be linked to specific impingement and combustion events. The results showed a sharp increase of the surface temperature during the flame impingement and an abrupt decrease as the flame disappeared.
|
|
