Effect of Thermocouple Size on the Measurement of Exhaust Gas Temperature in Internal Combustion Engines

Papaioannou, Nick; Leach, Felix; Davy, Martin

doi:10.4271/2018-01-1765

Cited by 11 publications

(15 citation statements)

References 28 publications

(50 reference statements)

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“…In terms of exhaust temperature, marginal increases were also observed with the SC piston with the biggest differences observed for the TP1 case (~7 °C). This translates into an increase in exhaust enthalpy of ~0.5 %, however considering the inherent errors associated with temperature measurement in internal combustion engines, the authors expect these gains to be underestimated [25].…”

Section: Discussionmentioning

confidence: 99%

The Effect of an Active Thermal Coating on Efficiency and Emissions from a High Speed Direct Injection Diesel Engine

Papaioannou¹,

Leach²,

Davy³

et al. 2020

SAE Technical Paper Series

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This study looked into the application of active thermal coatings on the surfaces of the combustion chamber as a method of improving the thermal efficiency of internal combustion engines. The active thermal coating was applied to a production aluminium piston and its performance was compared against a reference aluminium piston on a single-cylinder diesel engine. The two pistons were tested over a wide range of speed/load conditions and the effects of EGR and combustion phasing on engine performance and tailpipe emissions were also investigated. A detailed energy balance approach was employed to study the thermal behaviour of the active thermal coating. In general, improvements in indicated specific fuel consumption were not statistically significant for the coated piston over the whole test matrix. Mean exhaust temperature showed a marginal increase with the coated piston of up to 6 °C. However, the normalised exhaust enthalpy showed a reduction (apart from the higher speed/load conditions when no EGR was applied). Energy transfer to the coolant was reduced by as much as 1.5 percentage points, in agreement with the expected reduction in piston heat transfer, across all operating conditions. Finally, soot emissions were increased with the coated piston, with the biggest differences between the coated and non-coated pistons observed at the lower speed/load conditions.

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Section: Discussionmentioning

confidence: 99%

The Effect of an Active Thermal Coating on Efficiency and Emissions from a High Speed Direct Injection Diesel Engine

Papaioannou¹,

Leach²,

Davy³

et al. 2020

SAE Technical Paper Series

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“…It is seen that the use of the steel piston design results in consistent, small (~1.3 to 2.5%), but statistically significant decreases in mean exhaust gas temperature. A note on the detail of these exhaust temperature measurements is included in [25]. Table 3 details the changes in ignition delay, early phase combustion duration (10 -50% MFB), late phase combustion duration (50 -90% MFB) and the overall combustion duration (10 -90% MFB) for the steel piston relative to the aluminium.…”

Section: Resultsmentioning

confidence: 99%

Thermal Analysis of Steel and Aluminium Pistons for an HSDI Diesel Engine

Papaioannou¹,

Leach²,

Davy³

2019

SAE Technical Paper Series

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Chromium-molybdenum alloy steel pistons, which have been used in commercial vehicle applications for some time, have more recently been proposed as a means of improving thermal efficiency in lightduty applications. This work reports a comparison of the effects of geometrically similar aluminium and steel pistons on the combustion characteristics and energy flows on a single cylinder high-speed direct injection diesel research engine tested at two speed / load conditions (1500 rpm / 6.9 bar nIMEP and 2000 rpm / 25.8 bar nIMEP) both with and without EGR. The results indicate that changing to an alloy steel piston can provide a significant benefit in brake thermal efficiency at part-load and a reduced (but nonnegligible) benefit at the high-load condition and also a reduction in fuel consumption. These benefits were attributed primarily to a reduction in friction losses. In terms of energy transfer, switching to the steel piston design was shown to reduce heat transfer to the coolant, consistent with lower friction work and reduced conduction through the ring pack, and increase the energy transfer to the oil. Piston blowby was also greatly reduced. Ignition delay times and overall combustion durations were reduced with the steel piston design, possibly indicative of higher piston surface temperatures.

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“…This process has two caveats; first, the sensor indicates the tempera e f he he c e j c i a d he f id temperature which will be lower due to conduction and radiation heat transfer away from the junction. The effects of conduction and radiation errors in ICEs have been the subject of many studies in the past [11][12][13][14][15][16]. Figure 1 shows the various heat transfer modes that a thermocouple junction is exposed to when installed on the exhaust pipe of an ICE.…”

Section: Introductionmentioning

confidence: 99%

“…This schematic assumes that the gas is at a higher temperature than the junction and the wall at a lower temperature. This is not always the case and simulations have shown that during the period that the exhaust valves are closed, the junction can be at a higher temperature than the surrounding gas [15]. Papaioannou et al…”

Section: Introductionmentioning

confidence: 99%

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Improving the Uncertainty of Exhaust Gas Temperature Measurements in Internal Combustion Engines

Papaioannou

Leach

Davy

2020

Journal of Engineering for Gas Turbines and Power

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Accurate measurement of exhaust gas temperature (EGT) in internal combustion engines (ICEs) is a challenging task. The most common, and also the most practical, method of measurement is to insert a physical probe, for example, a thermocouple or platinum resistance thermometer, directly into the exhaust flow. Historically, consideration of the measurement errors induced by this arrangement has focused on the effects of radiation and the loss of temporal resolution naturally associated with a probe of finite thermal inertia operating within a pulsating flow with a time-varying heat input. However, a recent numerical and experimental study has shown that conduction errors may also have a significant effect on the measured EGT, with errors approaching ∼80 K depending on engine operating conditions. In this work, the authors introduce a new temperature compensation method that can correct for the combined radiation, conduction, and dynamic response errors introduced during the measurement and thereby reconstruct the “true” crank-angle resolved EGT to an estimated accuracy of ±1.5%. The significance of this result is demonstrated by consideration of a first law energy balance on an engine. It is shown that the exhaust gas enthalpy term is underestimated by 15–18% when calculated using conventional time-averaged data as opposed to using the mass-average exhaust enthalpy that is obtained by combining the reconstructed temperature data with crank angle-resolved exhaust flow rates predicted by a well-validated one-dimensional (1D) simulation.

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Effect of Thermocouple Size on the Measurement of Exhaust Gas Temperature in Internal Combustion Engines

Cited by 11 publications

References 28 publications

The Effect of an Active Thermal Coating on Efficiency and Emissions from a High Speed Direct Injection Diesel Engine

The Effect of an Active Thermal Coating on Efficiency and Emissions from a High Speed Direct Injection Diesel Engine

Thermal Analysis of Steel and Aluminium Pistons for an HSDI Diesel Engine

Improving the Uncertainty of Exhaust Gas Temperature Measurements in Internal Combustion Engines

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