Artículo Académico / Academic Paper

Recibido: 12-11-2024, Aprobado tras revisión: 08-01-2025

Forma sugerida de citación: Meneses, H.; Quitiaquez, W.; Quitiaquez, P.; Simbaña, I. (2025). “Regeneración de Componentes

Deteriorados de Combustión Interna Utilizados en Centrales Térmicas” (2025). Revista Técnica “energía”. No. 21, Issue II, Pp.

48-59

ISSN On-line: 2602-8492 - ISSN Impreso: 1390-5074

Doi: https://doi.org/10.37116/revistaenergia.v21.n2.2025.690

Esta publicación está bajo una licencia internacional Creative Commons Reconocimiento –

No Comercial 4.0 (https://creativecommons.org/licenses/by-nc/4.0/)

Regeneration of Deteriorated Internal Combustion Engine Components Used

in Thermal Power Plants

Regeneración de Componentes Deteriorados de Motores de Combustión

Interna Utilizados en Centrales Térmicas

H. Meneses1

0009-0001-5668-5016

W. Quitiaquez1

0000-0001-9430-2082

P. Quitiaquez1

0000-0003-0472-7154

I. Simbaña2

0000-0002-3324-3071

1Universidad Politécnica Salesiana, Quito, Ecuador

E-mail: hmeneses@est.ups.edu.ec, wquitiaquez@ups.edu.ec, rquitiaquez@ups.edu.ec,

2Instituto Superior Universitario Sucre, Quito, Ecuador

E-mail: isimbana@tecnologicosucre.edu.ec

Abstract

The generation of electric power through internal

combustion engines plays an important role in the world

economy. Exhaust cases and valves are critical engine

components and are subjected to high pressures and

temperatures. The additive remanufacturing technology

of mechanical components that have reached the end of

their useful life due to wear, through the L-DED laser

directed energy deposition method, proves to be an

effective method to obtain spare parts with similar or

even superior characteristics to a new part, extending the

product life cycle in the circular economy. The process

consists of obtaining 3D models through reverse

engineering, additive remanufacturing by L-DED and

final machining. It was determined through the study that

this methodology can be successfully applied to the

exhaust boxes and valves of internal combustion engines

for electric generation. The results obtained have shown

that this remanufacturing method is an effective solution

for the recovery of exhaust boxes and valves that have

completed their useful life and can be applied to other

engine elements, reducing the cost of the spare part

compared to a new one and bringing with it important

environmental benefits. In reference to the

remanufacturing time, it has been determined that the

application of the L-DED process in the exhaust boxes

and valves is 3943 and 3677 s respectively. In addition to

this time, the time used in the initial preparation and final

machining must be added; however, the time is

substantially less than the manufacturing of a new spare

part, which brings with it an increase in the availability of

these spare parts to perform scheduled maintenance in the

engines for power generation, contributing to improve the

efficiency of the national electric system.

Index terms−− Additive Remanufacturing, Reverse

Engineering, Circular Economy.

Resumen

La generación de energía eléctrica a través de motores de

combustión interna juega un rol importante en la

economía mundial. Las cajas y válvulas de escape son

componentes críticos del motor y están sometidos a altas

presiones y temperaturas. La tecnología de remanufactura

aditiva de componentes mecánicos que han finalizado su

vida útil debido al desgaste, a través del método de

deposición de energía dirigida por láser L-DED, resulta

ser un método eficaz para conseguir repuestos con

características similares e incluso superiores a un

repuesto nuevo extendiendo el ciclo de vida del producto

en la economía circular. El proceso consiste en la

obtención de los modelos 3D a través de ingeniería

inversa, remanufactura aditiva por L-DED y mecanizado

final. Se determinó a través del estudio que esta

metodología se puede aplicar con éxito en las cajas y

válvulas de escape de los motores de combustión interna

para generación eléctrica. Los resultados obtenidos han

demostrado que este método de remanufactura es una

solución eficaz para la recuperación de cajas y válvulas

de escape que han finalizado su vida útil y puede ser

aplicado a otros elementos de los motores reduciendo el

costo del repuesto en comparación con un nuevo y

trayendo consigo beneficios ambientales importantes. En

referencia al tiempo de remanufactura se ha determinado

que la aplicación del proceso L-DED en las cajas y

válvulas de escape son de 3943 y 3677 s respectivamente,

adicional a este tiempo se debe sumar el tiempo

empleado en la preparación inicial y maquinado final, sin

embargo, el tiempo es sustancialmente inferior a la

fabricación de un repuesto nuevo lo que trae consigo un

incremento de la disponibilidad de estos repuestos para

realizar los mantenimientos programados en los motores

para generación de energía contribuyendo en mejorar la

eficiencia del sistema eléctrico nacional.

Palabras Clave

−−

Remanufacturación aditiva,ingeniería

inversa, economía circular.

Edición No. 21, Issue II, Enero 2025

1. INTRODUCCIÓN

The mechanical components of internal combustion

engines that use reduced crude oil as fuel present wear

due to friction, fuel quality, accumulated hours of

operation, abrasive action of soot particles, due to the

formation of acids due to the sulfur content of the fuel,

high pressures and temperatures [1]. This causes a loss

of operating efficiency by increasing the clearances

between static and rotating components until the

maximum permissible wear is reached, which leads to

the cessation of the mechanism operation [2], [3].

Several of these engine components once they have

finished their useful life due to wear, are feasible to

recover to their original state through additive

remanufacturing processes or thermal spray processes

that allow obtaining high-quality components like a new

spare part thus extending the product life cycle in the

circular economy [4], [5]. The layer-by-layer additive

remanufacturing processes that are popularly known as

3D printing represent a new technology that achieves

good results in the circular economy [6]. This

technology allows maintaining the properties of the

additive material as well as the substrate and does not

generate oxide during process [7]. On the other hand,

several thermal spray processes produce high-quality

fusion depositions, with the disadvantage that they can

generate oxidation, thermal stress, and even phase

changes in the filler material and the substrate if the

application parameters of the process are not properly

controlled [8].

The following is a brief review of the literature

regarding the dimensional recovery of deteriorated

engine components. Rahito et al [4] conducted a study

of the principles and capabilities of using metal additive

technology, in the remanufacturing and refurbishment

of mechanical elements that have ended their useful life

due to use, to achieve product life cycle extension in the

circular economy. The study determined that the

applicable additive processes for remanufacturing are

direct energy deposition, powder bed fusion, and cold

spray technology. The researchers conclude that AM

technology is being used in more and more applications

due to the excellent results obtained, such as obtaining

elements with similar characteristics to new spare

parts [9].

Permyakov et al. [3] developed a methodology for

technological design, repair, and restoration of worn

mechanical elements, using methods for improving the

working layer of the element. The proposed

technological process for the restoration of mechanical

elements is a combination of surface plastic deformation

and non-abrasive antifriction finishing treatment. With

the application of this procedure, it is possible to restore

the elements that have suffered wear due to use,

prolonging their useful life. Peng et al. [10] developed a

multicriteria study for the selection and application of

the remanufacturing and restoration process of

crankshafts, with an approach that considers the

environmental, economic, and technical property impact

by applying the fuzzy technique of order preference by

similarity to the ideal solution. The study concludes that

the most suitable methods for crankshaft restoration

from the vision of the circular economy, based on the

proposed criteria, in order of application are brush

electroplating, plasma spraying, plasma arc coating, and

laser coating applying these restoration methods,

compared to their remanufacturing counterparts

represent a saving of 50 % of the total cost, 60 % of

energy and up to 70 % of materials.

Yin et al. [7] carried out a systematic review of the

advances in the cold sputtering process technology

(CSAM) for the additive manufacturing and repair of

spare parts. This study has shown that the repair or

manufacturing of elements with the CSAM process does

not distort the properties of the addition material, does

not generate oxide deposits, and preserves the

characteristics of the substrate, obtaining elements with

excellent physical and mechanical properties suitable

for reuse [11] However, this method has disadvantages

because the quality of the deposition depends on the

kinetic energy, producing the addition of the material by

the plastic deformation of the raw material particles,

being necessary to perform a subsequent heat treatment

to improve the quality additionally, the finish has a

relatively high roughness, so machining must be

performed to give the final finish to the element.

Xiang et al. [12] developed a method for the

determination of the optimum moment to perform active

remanufacturing of a mechanical element. As an

illustrative example, the oil cylinder of a concrete truck

that has suffered wear due to use was used. Active

remanufacturing is based on remanufacturing or

refurbishing a product before discarding it. The

determination of the exact moment when

remanufacturing should be performed is of vital

importance because it facilitates the technique, reduces

costs, and minimizes waste generation in line with

environmental protection. The study considered the

relationship between environmental impact and

manufacturing cost throughout the product life cycle.

Through the method developed it was determined that

the right time for active remanufacturing is when the

product performance begins to degenerate.

Barragán et al. [13] carried out analytical and

experimental studies to determine the most suitable

combination for the application of the additive

Meneses et al. / Regeneration of deteriorated internal combustion engine components used in thermal power plants

manufacturing method called laser-directed energy

deposition (L-DED). The variables analyzed are

deposition speed, laser power, material flow rate, and

inert gas flow. Applying the best-performing

combination, they fabricated thin-walled structures and

solid components using an L-DED head and a powder

feed system. They deposited Inconel 625 on a substrate

of AISI 304 material. The best results are related to

higher particle concentration, quality depositions, and

optimal cooling rates. Additionally, with this

combination, they obtained a significant reduction in

metal powder and gas consumption. The increase in

mass flow generates an increase in coating hardness, i.e.

these variables are directly related.

The remanufacturing of complex geometries is very

costly and requires advanced technology to achieve a

reliable result. Zhao et al. [14] developed a

methodology for the remanufacturing of compressor

blades, which includes reverse engineering, surface

modeling, recovery by additive processes with direct

laser, and final machining. First, the point cloud is

obtained through a scanner, then an adaptive

reconstruction is performed, and the 3D digital model of

the part is obtained [15], where the damage or wear can

be located, with which the additive recovery process is

determined through laser and subsequent milling

operation with multi-axis equipment. This procedure

was effective, so the results show that the applied

procedure of reverse engineering, additive process with

laser, and subtractive milling is an effective solution for

blade remanufacturing. This methodology can be

applied to the remanufacturing of other elements with

complex geometries.

Shrivastava et al. [16] performed an analysis of the

repair of aerospace components through the directed

energy deposition (DED) process, applying Inconel 718

material. The study focused on identifying the

challenges encountered in the repair process through the

DED process from the geometrical and metallurgical

point of view of the component. Some problems were

observed, such as the existence of micropores near the

edge of the repaired component and the variation of the

microstructure, about the increase of the deposition

height, which influences the increase of the preparation

cost of the component before the final use, despite

which it is concluded that the DED technique is a cost-

effective alternative in the recovery of high-value

elements, compared to the replacement by a new

component.

The purpose of this study is to analyze and find the

most suitable additive remanufacturing method to

recover used spare parts that have reached the end of

their useful life from Mitsubishi Man 18V 40/54

internal combustion engines, contributing to the circular

economy and the environment, in addition to saving

economic resources. This document presents four

sections. In the first section, an exploration of the state

of the art of technological advances in additive

remanufacturing is carried out. In the second section,

the results and methods used are presented, focusing on

the mathematical models applicable to the development

of the study. In the third section, the results obtained are

analyzed using comparative tables and graphs. Finally,

in the conclusions section, the results are mentioned,

where the most adequate method is determined in

technical, economic, and environmental terms to carry

out the dimensional recovery of the spare parts of

motors for electric power generation that have finished

their useful life.

2. MATERIALS AND METHODS

The research is carried out in a generation plant with

6 generators driven by Mitsubishi Man 18V 40/54

internal combustion engines. Table 1 shows the main

characteristics of these engines.

Table 1. Characteristics of Mitsubishi Man 18V 40/54 motors.

Parameter

Specification

Manufacturer

Mitsubishi Man

Model

18V 40/54

Engine power

7800 HP

Fuel

Reduced crude oil, diesel

Thermodynamic principle

4 times

No. of Cylinders

Cylinder bore

400 mm

Piston stroke

540 mm

The mechanical components of internal combustion

engines wear due to the physical operating conditions.

Additionally, acid formation occurs due to the sulfur

content of the fuel, which causes corrosive wear [17].

This war results in decreased operating efficiency due to

increased clearances between static and rotating

components. Wear occurs whenever there is rotary

motion between two contacting elements [18]. In the

production line, the failure of certain components can

lead to a total shutdown [19]. If a potential failure is

detected, it is necessary to perform maintenance

immediately before triggering serious damage [20].

Optimization of maintenance plans leads to significant

Edición No. 21, Issue II, Enero 2025

benefits in increasing the reliability of equipment and

systems [21], [22]. In the power industry, the reliability

of power plants is crucial to meet demand [23]. To keep

motors in optimal operating condition, spare parts and

consumables are necessary to comply with the

established maintenance plan.

Determination of the elements to be recovered

In Mitsubishi Man 18V 40/54 internal combustion

engines, various elements experience wears due to the

operating conditions to which they are subjected, for

example, the exhaust box, the fuel cam, and the cylinder

liner, among others. However, some of these element’s

show wearing more frequently, which requires their

replacement at relatively short intervals. Fig. 1 shows a

Pareto diagram, which shows the relationship between

the average period in which spare parts show non-

recoverable wear and the number of elements per

engine, which allows determining the spare parts to be

remanufactured as part of this study:

Figure 1: Pareto diagram, elements subject to wear in the engine

Considering the period in hours in which the

elements show wear outside the admissible range, the

number of elements for each engine, and other factors

such as the delivery time of the new spare part from the

supplier, the elements that will be part of this study have

been determined and they are the exhaust box which is

the element that is installed in the cylinder head and on

which the exhaust valve is mounted (See Fig. 2) and the

exhaust valve which is the element that is

synchronously driven by the camshaft through the

rocker's arm opens and closes which allows the

thermodynamic cycle of the engine to be fulfilled (See

Fig. 3). These elements suffer wear in the contact

surfaces between the valve and the exhaust box, it is this

area that will be recovered to the original dimensions.

Figure 2: Exhaust box

Figure 3: Exhaust valves

Remanufacturing strategies

The proposed remanufacturing method consists of

several processes. In general, it starts with the collection

of wear information of the element to be

remanufactured through reverse engineering (RE)

technology. For reverse engineering, a 3D laser scanner

is used to obtain the geometry of the worn element.

Through the RE system, the geometric reconstruction of

the element is achieved, which is the basis for the

subsequent application of the directed energy deposition

(DED) method and final subtractive machining through

a CAD/CAM system. Fig. 4 details the process.

Meneses et al. / Regeneration of deteriorated internal combustion engine components used in thermal power plants

Figure 4: General flow diagram of the remanufacturing process

Process of obtaining the 3D models of the worn

elements

Internal combustion engines work at high

temperatures and pressures; in the case of analysis, the

fuel used has a relatively high percentage of sulfur (1 %

v/v). Because of prolonged periods of operation, various

components tend to experience wear, deformation, and

even breakage. It is important to note that each of these

defects can be unique, even if they affect identical

engine elements. Therefore, the proposed

remanufacturing process must have the ability to adapt

to these variations by specifically addressing each type

of deterioration.

Obtaining accurate geometrical data on the elements

destined for remanufacturing is critical. It is therefore

imperative to employ a suitable system to obtain 3D

models with accurate information. In this context, it has

been chosen to use a 3D laser scanner, whose

specifications are detailed in Table 2, has been selected

after considering several physical variables applicable to

the process, such as the number of complex details of

the elements and the required appreciation. Once the

element has been scanned, a point cloud is generated

and processed to obtain the 3D model.

Table 2. Main technical characteristics of the 3D scanner used

Type

Model

Series

Powe

Accurac

y (mm)

Sampl

Densit

Laser

scan

ACADE

MIA 50

937000

18V

—1A

0.025

Errors often occur during the scanning process of the

worn elements due to light interferences, complicated

geometries, and hardly visible areas, resulting in

inaccurate data. Therefore, it is necessary to perform

processing the data obtained by the 3D scanner through

software in this case, the VX Model software has been

used. The process to obtain the final 3D model is

divided into some steps that are detailed below:

debugging of the point cloud data, filling of unneeded

details, and optimization in the use of computational

resources. With this, results are obtained in less time.

The 3D models obtained with the scanner are shown in

Figs. 5 and 6. Fig. 5 shows the exhaust box, which is the

element in which the valve is housed, the guides, the

fastening system, and the valve turning system. In

addition, at the top, the seating track can be seen, which

is the area that contacts the exhaust valve and

hermetically seals the engine combustion chamber in

each cylinder. The seating track is subjected to the

temperature of the combustion chamber (500 °C +- 10

%).

Figure 5: 3D model of the exhaust box obtained through the

scanner

Edición No. 21, Issue II, Enero 2025

Fig. 6 shows the exhaust valve, which is the element

that is directly exposed to the combustion chamber of

the engine and performs the opening and closing in a

synchronized manner through the camshaft to allow the

combustion process in the chamber and subsequent

evacuation of the exhaust gases to the manifold. The

exhaust valve has in the upper part of the shaft, a

mechanism that allows this element to rotate 10 degrees

clockwise in each opening process. Like the exhaust

housing, the valve is subjected to temperatures of

around 500 °C and pressures between 110 and 120

kg/cm2. In the lower part of the exhaust valve is located

the seating track, which is the area that contacts the

exhaust box and performs the hermetic seal in the

combustion chamber.

Figure 6: 3D model of the exhaust valve obtained through the

scanner

Fig. 7 shows the assembled assembly where the

seating tracks and the arrangement of the housing and

exhaust valve when in operation can be seen.

Figure 7: Assembled exhaust valve housing assembly

The exhaust valve box and valve are elements that

are exposed to high temperatures and pressures, as well

as chemical corrosion due to the formation of sulfuric

acid (H2SO4) during the combustion process inside the

chamber due to the sulfur content of the fuel.

Additionally, it must be considered that the exhaust

valve opens and closes 200 times per minute because

the engine works at 400 revolutions per minute (RPM)

continuously. Therefore, the proper selection of the

filler material for the additive remanufacturing of the

seating tracks is essential.

Verification of the remanufacturing feasibility of

the used spare part

Fig. 8 details the process to determine the feasibility of

spare parts recovery:

Figure 8: Process flow diagram to determine the feasibility of

spare parts recovery

Remanufacturing process through Directed

Energy Deposition (DED)

Directed energy deposition (DED) consists of the

application of additional raw material in the form of

powder or wire on a substrate. To perform this

application, an energy source is placed on the substrate,

which can be a laser beam, an electron beam, or a

plasma. In this way, a small melt pool is formed, and the

material is continuously deposited layer by layer. The

deposition is performed by a computer-controlled head

based on the CAD file of the element being

remanufactured [24]. When the filler material enters the

melt pool, it melts instantaneously increasing the

volume of the liquid material. When the laser moves

away, the molten material becomes solid [25]. The

melting zone is protected from oxidation by shielding

gas, the gas is usually argon [26].

The DED process adapts to the surface conditions of

the substrate, which is an important feature for repairing

components. The case and exhaust valves, which are the

subject of this study, have a high manufacturing cost.

Remanufacturing is a substantial cost and time savings

compared to a new replacement [27]. Each of the power

sources produces different characteristics in the

application related to the size of the elements that can be

processed, the resolution of the details, and the rate of

additional material disposition. For the present study,

considering the dimensional characteristics and

Meneses et al. / Regeneration of deteriorated internal combustion engine components used in thermal power plants

complexity of the elements to be remanufactured, laser-

directed energy deposition (L-DED) was the most

suitable process.

L-DED technology is suitable for the repair of worn

elements, it also minimizes erosion or future damage of

the repaired part [28]. The application of additional

material in powder form requires a laser power of 500 to

1000 W [24]. In the case of the application of additional

material in the form of wire, the power must be higher

which produces lower-quality surface finishes, this is a

disadvantage, according to the study conducted through

a literature review, the most appropriate is the L-DED

process with addition material in powder form for this

case study. The parameters for the application of the L-

DED process in the additive remanufacturing of used

spare parts are fundamental to obtaining successful

results. These parameters include the selection and

optimization of laser temperature, material deposition

rate, metal powder flow rate, laser power, and beam

diameter, among others. In addition, it is necessary to

consider the characteristics of the material used, such as

its thermal conductivity, mechanical strength, and

physical properties, to determine the ideal parameters.

The control of these parameters will ensure the

structural integrity of the remanufactured parts and

guarantee their correct operation once installed [29].

Selection of filler material

The exhaust valve is subjected to temperatures of

around 500 °C, produced in the combustion chamber of

the engine. The pressures at this point are in order of

110 to 120 kg/cm2. The exhaust box is subject to similar

conditions. The material of manufacture of the exhaust

box and valve is Nimonic 80A. This superalloy is

widely used in diesel engines, especially in exhaust

valves [30]. The selected filler material must meet the

characteristics of compatibility with the material of

manufacture of the housing and exhaust valve and must

also withstand the operating conditions of these

elements. The proper selection of the filler material is

fundamental to avoiding difficulties due to the

differences between the physical and mechanical

properties of the filler material about the substrate.

These differences in material properties can cause

residual stress that result in cracks and spalling [31].

Two materials have been determined that meet the

necessary characteristics for the operating conditions of

the spare parts to be remanufactured in the present

study, these are INCONEL 625 and INCONEL 718.

The material Inconel 625 is used in industry in

environments with temperatures ranging from -150 to

over 1000 °C [32]. This alloy has excellent yield

strength, fatigue, and creep resistance characteristics as

well as excellent resistance to oxidation, corrosion, and

frictional wear in aggressive environments. Table 6

shows the values of the properties described. Table 4

details the chemical composition of this material.

Inconel 718 material has good creep resistance and

increased fatigue resistance at temperatures up to 700

°C. Inconel 718 has a higher tensile strength than

Inconel 625. The elongation is 8% lower than Inconel

625 [33], [34]. In addition, Inconel 718 has higher

strength at elevated temperatures and has good

resistance to frictional wear, hot corrosion, and fatigue.

Table 3 shows the composition of this material.

In general terms, these materials show differences in

density, tensile strength, corrosion resistance, oxidation

resistance, thermal conductivity, coefficient of thermal

expansion, and elastic modulus. Table 3 shows the

results of the mechanical characteristics of tensile

strength and yield strength obtained for Inconel 625 and

Inconel 718 materials after having been applied on a

substrate through the DED process.

Table 3. Tensile properties of Inconel 625 and Inconel 718

manufactured using the DED technique.

Alloy

Application

method

Direction

of material

application

Mechanical

properties

Reference

Inconel

625

DED

Uniform

horizontal

and vertical

direction

for each

pass

Yield

strength -

500 MPa

Tensile

strength

733 MPa

[33], [35]

Inconel

718

DED

Uniform

horizontal

and vertical

direction

for each

pass

Yield

strength -

740 MPa

Tensile

strength

1050 MPa

[33], [36]

From the results shown in Table 3, it can be

concluded that the Inconel 718 material presents

superior mechanical properties after being applied on a

substrate through the DED process; however, these

mechanical properties are not determinant in the case of

this study according to the operating circumstances of

the parts studied.

Final machining process with CAD/CAM

Through the reverse engineering process and post-

processing with SOLIDWORKS design software, the

three-dimensional models of the parts have been

obtained, considering all their measurements and

characteristics. The geometries of the elements to be

repaired are shown in Figs. 9 and 10.