Coolant Flow Rate Research Articles

Hydrogen ortho-para conversion: process sensitivities and optimisation

Liquid hydrogen has potential as a storage vector for large-scale hydrogen transportation. Hydrogen liquefaction is however a highly energy intensive process, particularly due to the necessary exothermic spin-isomer conversion from ortho- to parahydrogen. We explore the operation of the main cryogenic plate-fin heat-exchangers (PFHXs) used in hydrogen liquefaction; simultaneous dynamic processes occurring within the PFHX include the heterogeneously catalysed spin-isomer conversion, heat transfer and pressure loss. In this work, these coupled processes are simulated for a 100 tonne/day hydrogen reactant cooled by a helium refrigerant in a PFHX. For the process configuration utilised in this work, a reactor volume of 24.0 m3 and a coolant flow rate of 600 tonne/day were necessary to achieve and outlet parahydrogen fraction of 0.99. Pressure drop through the PFHX packed bed was consistently negligible. We also explored the sensitivity towards model parameters. The outlet parahydrogen fraction is determined to be considerably (∼10 times) more sensitive to reaction rate kinetics relative to heat transfer: therefore, the reactor geometry will be primarily determined by conversion kinetics. The current quantitative understanding of these rate kinetics is however limited. Future experimental research thus needs to focus on quantifying ortho- to parahydrogen kinetics.Destination: Chemical Engineering and Processing: Process Intensification

Turbine Vane Passage Experiments Documenting Evolution of Secondary Flows With Changes in Combustor Coolant Injection Flowrates

Abstract A secondary flow system with a dominant passage vortex pattern has been observed in many gas turbine vane passage studies in which there is no upstream coolant injection or only near-passage endwall coolant injection (no combustor cooling). However, it was shown in recent studies that combustor coolant introduced upstream of the vane passage changes secondary flow patterns in the passage. This results in a different secondary flow vortex system, called the “impingement vortex” system. It was discussed in recent literature having combustor coolant injection. Until now, there has been no study on how increases in combustor coolant momentum effect transition from the passage vortex system to the impingement vortex system. Such a study is presented in the present paper. Velocity component measurements are taken using a five-hole probe at three axial locations in the vane passage to document secondary flow development throughout the passage. Four combustor coolant flowrate cases are considered along with a comparison case having no coolant injection. It is shown that as the combustor coolant flowrate increases, the passage vortex system weakens and, at a sufficiently high combustor coolant flowrate, the impingement vortex system appears. Knowing the detailed flow physics of this transition between the two secondary flow systems is helpful for turbine thermal designers who wish to understand how secondary flows transport coolant within the turbine vane passage.

Investigation of assisted heating cold start strategies from -40 °C for proton exchange membrane fuel cell stack

ABSTRACT To investigate the effects of varying assisted heating methods on the proton exchange membrane fuel cell (PEMFC) stack in extremely low-temperature conditions, a quasi-two-dimensional dynamic model is developed. This model considers the effect of cooling channels on cold starts and has been verified by experimental data. The limited self-start ability of an adiabatic PEMFC is tested, and the result shows that the PEMFC cannot start successfully from −40°C. Then, the effects of resistance wire heating and recycled coolant heating methods on the PEMFC stack are analyzed at −40°C. For the resistance wire heating method, due to the limitation of thermal conductivity, higher heating power can hardly raise the temperature of the middle cells in the stack. Furthermore, only stacks with fewer than 6 cells can start successfully. For the recycled coolant heating method, the heat can be effectively transferred to the internal zone of the stack through the coolant. The maximum temperature difference in the stack is decreased (from 32.43°C to 7.64°C, 308.6 mW cm−2) with higher coolant flow rates. However, higher heating power is needed to achieve a successful cold start (205.8 mW cm−2 under 0.01 m s−1, 308.6 mW cm−2 under 0.05 m s−1). In summary, the recycled coolant heating method is more suitable for the cold start of the stack at −40°C.

NUMERICAL INVESTIGATION OF A SERPENTINE-TUBE COLD PLATE COOLED LITHIUM-ION BATTERY UNDER WIDE PARAMETRIC CONDITIONS

This paper examines the thermal management of a commercial 20 A h lithium ferro phosphate battery with the cold plates containing the serpentine tube structure, which is frequently preferred in heat exchanger applications. A numerical analysis is performed to explore the battery surface temperature distribution under varying operating conditions. In the study, an experimentally verified electrochemical thermal compound model was created and temperature distributions at the end of discharge at 1C, 3C, and 5C rates are obtained. The effects of different inlet temperatures (15°C, 25°C, and 35°C) and volumetric flow rates (0.1 L/min, 0.6 L/min, and 1.1 L/min) of the coolant on the two vital parameters of battery thermal management - maximum battery temperature and maximum battery temperature difference - are investigated for each discharge rate. As a key finding in this study, there is an acceleration of temperature variation from the middle part of the battery with the minimum temperature to the terminals with the maximum temperature, at the end of the discharge, in the use of a serpentine cold plate. Under the conditions where the coolant flow rate is maximum and the inlet temperature is minimum, the highest maximum temperature difference is 14.4°C, while the lowest maximum temperature difference is 10.8°C under the conditions where the coolant flow rate is minimum and the inlet temperature is maximum. Besides, the correlation equations in which the adjusted R<sup>2</sup> values for maximum battery temperature difference and maximum battery temperature are 98.0% and 99.6%, respectively, are developed.

Numerical simulation and analysis of lithium battery heat dissipation based on multi-objective optimization

In order to study the heat dissipation characteristics of lithium batteries, a staggered bi-directional flow cooling method is designed and numerical simulations are established using CFD in this paper with a circular battery as the research object. Since the optimal operating range of Li-ion battery is 293.15-313.15 K and the maximum temperature difference is not higher than 5 K, the maximum temperature and maximum temperature difference are selected as the optimized design objectives. Firstly, the temperature field of the round lithium battery with discharge multiplier 3C working at ambient temperature 308.15 K is studied, and an orthogonal test design is carried out for three factors: battery pack embedding distance, coolant flow rate and coolant temperature, and the best combination of orthogonal test is selected by extreme difference analysis and analysis of variance. Secondly, in order to further verify the heat dissipation efficiency of the battery pack, a back propagation neural network with multi-objective optimization algorithm is proposed, and the optimal heat dissipation method of the numerical simulation is obtained by parameter solution and simulation analysis using the parameter range of the orthogonal test as the constraints of the multi-objective optimization. The results show that this optimized way of battery pack heat dissipation has a significant improvement for the maximum temperature, and non-e of them will exceed its working range; compared with the 3.39 K obtained from the orthogonal test design, the maximum temperature difference of the battery pack calculated by the multi-objective optimization is 3.15 K, which is reduced by 7.08%.

Effects of Active Cooling Techniques to Improve The Overall Efficiency Of Photovoltaic Module- An Updated Review

Our scientists have struggled for the last few decades to save the nation from the harmful emission caused by burning fossil fuel and restore enormous solar radiation energy. Despite their hard labor in this field, only 12-16% of solar radiation is converted into electrical energy. The major part of it is wastage as heat that causes to rise of panel temperature and lowers its efficiency. The aim of the review is to find out the cost-effective and efficient active cooling methods of solar photovoltaic (SPV) cell to improve their overall performance. Therefore, thirty-two active cooling techniques are thoroughly studied, compared their results from more than a hundred papers. Cooling of the SPV panel is a function of optimum spraying timing, coolant flow rate, wind condition, the distance between flow points (nozzle) to the panel, and solar radiation. The major facts revealed that the efficiency of the PV panel is optimum within 25-300C, and the panel's performance decreases by 0.5% for each 10C rise of panel temperature from standard temperature. The best active cooling method revealed that the electrical efficiency of the PV module could be increased by 57% with a lowering of module temperature by 32% in hot summer.

Research on Performance Optimization of Liquid Cooling and Composite Phase Change Material Coupling Cooling Thermal Management System for Vehicle Power Battery

The serpentine tube liquid cooling and composite PCM coupled cooling thermal management system is designed for 18650 cylindrical power batteries, with the maximum temperature and temperature difference of the power pack within the optimal temperature operating range as the target. The initial analysis of the battery pack at a 5C discharge rate, the influence of the single cell to cooling tube distance, the number of cooling tubes, inlet coolant temperature, the coolant flow rate, and other factors on the heat dissipation performance of the battery pack, initially determined a reasonable value for each design parameter. A control strategy is used to regulate the inlet flow rate and coolant temperature of the liquid cooling system in order to make full use of the latent heat of the composite PCM and reduce the pump’s energy consumption. The simulation results show that the maximum battery pack temperature of 309.8 K and the temperature difference of 4.6 K between individual cells with the control strategy are in the optimal temperature operating range of the power battery, and the utilization rate of the composite PCM is up to 90%.

Performance evolution in machining parameter of Al-Si (LM6) alloy using neural network

The global manufacturing age has increased competition in the manufacturing sector as markets become more agile and customer-focused. Because of the fierce rivalry, manufacturers are paying more attention to automation. In the last several decades, computer numerically controlled (CNC) machine tools have been utilized to achieve complete automation in machining. The artificial neural network theories are used in this research to train a solution for the problem of selecting machine setup settings for a turning operation. A collection of input and output values can be mapped out by an artificial neural network. A network may be used to anticipate output values for a certain set of input values once it has been trained. Process inputs like cutting speed, feed, depth of cut, and coolant flow rate can be generated by a trained program, as can their related process outputs like surface finish. Forward mapping of process inputs and outputs is accomplished using back propagation neural networks in this approach. The optimum machine setup parameter may then be selected interactively using these networks. To solve the model, a MATLAB program has been created. The experiment's findings are verified using a neural network.

A Novel Method for Heat Exchange Evaluation in EV

With the growing global energy and environmental problems, electric vehicles that are both environmentally friendly and cost effective have seen rapid growth. An electrified vehicle’s effective thermal management must include all of the vehicle’s systems. However, optimizing the thermal behavior of each component is insufficient. A lithium-ion battery’s operating temperature has a significant impact on its performance. When working at low temperatures, the internal resistance of lithium-ion batteries increases, the available energy and power of the system decreases, and lithium precipitation caused by low-temperature charging may cause safety issues; high-temperature operation and temperature inconsistency between battery cells will cause accelerated ageing of the battery, which may result in safety issues such as thermal runaway. As a result, to keep the temperature of the battery module under control, electric cars require a strong thermal management system. Thermal management must be handled at the system level to maximize the vehicle’s overall performance. The integrated thermal management system for electric vehicles has the potential to significantly increase vehicle energy efficiency. However, it’s construction is complicated due to the thermal requirements of the battery and cabin. In this research, a multi-channel liquid cooling system with a serpentine wavy structure was used to conduct an experimental thermal investigation of a lithium-ion battery pack. The suggested cooling system’s capabilities was examined under various charge/discharge scenarios using varied coolant flow rates and pumping power. The findings revealed that the suggested cooling system was successful across a variety of charging and discharging settings, with most of the tested scenarios achieving a maximum temperature difference.

Temperature Control Design with Differential Evolution Based Improved Adaptive-Fuzzy-PID Techniques

This paper presents the design and performance analysis of Differential Evolution (DE) algorithm based Proportional-Integral-Derivative (PID) controller for temperature control of Continuous Stirred Tank Reactor (CSTR) plant in chemical industries. The proposed work deals about the design of Differential Evolution (DE) algorithm in order to improve the performance of CSTR. In this, the process is controlled by controlling the temperature of the liquid through manipulation of the coolant flow rate with the help of modified Model Reference Adaptive Controller (MRAC). The transient response of temperature process is improved by using PID Controller, Differential Evolution Algorithm based PID and fuzzy based DE controller. Finally, the temperature response is compared with experimental results of CSTR.

Some technological aspects of cleaning pipes of heat exchangers from solid scale deposits

This article discusses possible solutions to one of the problems associated with the low efficiency of existing thermal power plants. These factors are due to both the depreciation of equipment and the lack of any effective technologies for intensifying heat and mass transfer processes. The relevance of research topics is also confirmed by the fact that at the state level it is proposed to legally oblige the subjects of the heat and power industry to carry out preventive measures aimed at optimizing existing enterprises. The description of the reasons for the occurrence of scale deposits that appear in the in-line cavities is given. Due to the fact that the thermal conductivity of solid deposits is much less than the thermal conductivity of the metals from which the heat exchanger tubes are made, they significantly reduce the intensity of the processes and the intensity of heat transfer. Solid deposits lead to a decrease in the coolant flow rate, an increase in fuel consumption and a violation of the technological mode of operation of the entire heat exchange unit. The authors analyzed various technological aspects of various methods for cleaning heat exchanger tubes from solid scale deposits, on the basis of which the advantages of the electrohydraulic treatment method are substantiated. A schematic diagram of the device is given and a brief description of the method of cleaning the pipes of heat exchangers from solid scale deposits is given using electro-hydro-pulse action. The results of the application of this technology for cleaning heat exchange pipes at specific heat and power enterprises are shown, which confirm its advantages over other cleaning methods, both in terms of processing time and energy costs. The influence of the degree of purification of heat exchange pipes from solid deposits on the thermophysical parameters and efficiency of the heat exchanger is considered.

ASSESSMENT OF THE OPERABILITY OF THE WATER HEATING SYSTEM, NOT RELEVANT TO THE PROJECT

When designing water heating systems, it is necessary to avoid unjustified use of excess equipment, exceeding diameters beyond the required values, etc. In reality, there are deviations from the project during installation, which lead to the need to revise the parameters of the system's operability. One of the cases is the replacement of pipelines of one diameter with another. Consideration of the prospects for the operation of such a heating system by example is the purpose of this work.
 For example, the water heating system in a residential 11-storey building in Brest (Belarus) built in 2019 is considered. The house has designed an apartment-by-apartment two-pipe horizontal water heating system with the installation of heat meters for each apartment. When installing the heating system, the apartment-by-apartment branches of the heating system were mounted with polyethylene pipelines with a diameter of 18×2,5 mm and 14×2 mm instead of the design 25×3,5 mm and 16×2 mm.
 To analyze the prospects for the functioning of the designed heating system, calculations of hydraulic resistances in the system at maximum coolant flow rates were performed, as well as their correlation with the parameters of the pumping equipment installed in the individual heating point.
 Calculations have shown that the installed pump is sufficient for the operation of the heating system with the actual diameters of the pipelines. Thus, the actually applied pipe diameters do not adversely affect the performance of the heating system in question.

Numerical Study of Liquid Metal Turbulent Heat Transfer in Cross-Flow Tube Banks

Heavy liquid metals (HLM) are attractive coolants for nuclear fission and fusion applications due to their excellent thermal properties. In these reactors, a high coolant flow rate must be processed in compact heat exchangers, and as such, it may be convenient to have the HLM flowing on the shell side of a helical coil steam generator. Technical knowledge about HLM turbulent heat transfer in cross-flow tube bundles is rather limited, and this paper aims to investigate the suitability of Reynolds Average Navier–Stokes (RANS) models for the simulation of this problem. Staggered and in-line finite tube bundles are considered for compact (a=1.25), medium (a=1.45), and wide (a=1.65) pitch ratios. The lead bismuth eutectic alloy with Pr=2.21×10−2 is considered as the working fluid. A 2D computational domain is used relying on the k−ω Shear Stress Transport (SST) for the turbulent momentum flux and the Prt concept for the turbulent heat flux prediction. The effect of uniform and spatially varying Prt assumptions has been investigated. For the in-line bundle, unsteady k−ω SST/Prt=0.85 has been found to significantly underpredict the integral heat transfer with regard to theory, featuring a good to acceptable agreement for wide bundles and Pe≥1150. For the staggered tube bank, steady k−ω SST and a spatially varying Prt has been the best modeling strategy featuring a good to excellent agreement for medium and wide bundles. A poor agreement for compact bundles has been observed for all the models considered.

Potential assessment of transcritical CO2 secondary loop heat pump for electric vehicles

The excellent heating performance and environmental advantages of the transcritical CO2 heat pump system make it a great fit for the electric vehicles (EVs). However, the high operating pressure leads to the possibility of excessive CO2 concentration in the cabin. To ensure the safety of passengers, a secondary loop (SL) system is proposed. In this study, we make a comparison between the traditional direct (TD) system and the SL system for an EV. The results show that the optimal coolant flow rate, with a range of 0.56 to 1.36 L/min in heating mode and 5.60 to 8.80 L/min in cooling mode, can increase the COP of the SL system in all working situations. In the heating mode, the COP of the SL system is 13.98% to 21.96% lower than that of the TD system, and the cruising range of the EV is reduced by 1.4 km ∼ 10.0 km. In cooling mode, the COP of the SL system is 16.95% to 22.45% lower than that of the TD system, and the cruising range has a reduction of 7.7 km ∼ 20.9 km. Results demonstrate that running the SL system in cooling mode rather than heating mode is more detrimental to EVs.

Numerical decoupling of the effect of internal cooling and external film cooling on overall cooling effectiveness

In modern aero-engine turbine blades, the coolant flows from the internal cooling channel and out through the film hole, forming a coolant coverage over the blade surface to isolate the high-temperature gas. Essentially, the cooling system can be divided into parts with internal cooling and external film cooling; in particular, external film cooling includes coolant coverage (film cooling) and bore cooling (cooling within the film hole). Accordingly, it is important to quantitatively analyze the effects of these three cooling parts (internal, bore, and film cooling) on the overall cooling effectiveness, which can help improve the design of turbine blades. To this end, in this study, the numerical decoupling method was used to investigate the relationship between the overall cooling effectiveness of two plate cooling structures and three cooling parts. Considering blowing ratios of 0.25, 0.5, 1, and 1.5, it was found that the blowing ratio and film hole position have considerable impacts on the overall cooling effectiveness of a smooth model; however, the overall cooling effectiveness of an impingement-effusion model was deemed insensitive to the film hole position. Furthermore, in the case of a small blowing ratio (M = 0.25), the internal heat transfer enhancement caused by impinging jets was less than that due to increased coolant flow rates. In the regions located upstream of each film hole exit, bore cooling had significant effects on the overall cooling effectiveness; particularly, these effects were more pronounced in the smooth model. Moreover, for a blowing ratio of 0.25, film cooling was dominant across all the cooling parts. With an increase in the blowing ratio, the influence of bore cooling grew rapidly, gradually replacing film cooling. Additionally, as the blowing ratio increased to 1.5, the effect of internal cooling exceeded that of film cooling. This work and its results are expected to serve as guidance for the design of turbine blade cooling structures.

Flow structures and heat transfer characteristics in a vaneless counter-rotating turbine cavity with different cooling inflows

The cooling air is used in the gas turbine to prevent the hot gas ingress and overheating of turbine disks. In this paper, the flow structures and heat transfer characteristics of vaneless counter-rotating turbine (VCRT) with different types of cooling inflows are numerically analyzed. The three-dimensional unsteady Reynolds-Averaged Navier-Stokes (URANS) equations with a Shear Stress Transport (SST) turbulence model are adopted. The results reveal that the inertia force, rotating effect and mainstream dominate the flow fields in VCRT cavity. The axial cooling inflow promotes the heat transfer characteristic in low pressure rotor (LPR) disk meanwhile the radial cooling inflow improves the heat transfer performance in high pressure rotor (HPR) disk. The vortexes interaction, viscous dissipation and heat transportation result in the decrease of heat transfer characteristic in the high radius region of rotor disk. The combined cooling inflow is adopted to solve the problem. It is the combination of radial cooling inlet and high position cooling inlet. The cooling air injected axially from the high position cooling inlet moves outward along the HPR disk which enhances the heat transfer characteristic. It is found that the Nusselt number and the amount of cooling air is not the simple linear relationship. The Nusselt number in HPR disk no longer increases if the high position cooling flow rate exceeds the threshold value. Compared with other types of cooling inflows, the needed amount of cooling air reduces when the combined cooling inflow is adopted. There is an optimum combined cooling flow rate which obtains the excellent heat transfer characteristics in the HPR disk.

Design optimization of plate-fin heat sink with forced convection for single-module thermoelectric generator

Thermoelectric generators (TEGs) often use plate-fin heat sinks as cold side heat exchangers under forced convection. The available net electrical power obtained from these TEGs corresponds to that generated (Seebeck effect) minus that consumed (cooling fan). Generation and self-consumption have different trends as a function of the air flow speed, so a maximum of the net electrical power is expected when varying the cooling flow rate. Here, a semi-analytical model was developed to predict the maximum net electrical power of a single TEG module with a plate-fin heat sink with non-bypassed forced convection. The model was successfully validated with experimental data. It was applied to determine the heat sink design (fin thickness and fin-to-fin distance) that optimized the net electrical power for given values of hot source temperature, TEG properties, and duct cross-section. Numerical results indicated that the optimal dimensions of the plate-fin heat sink depended, among others, on the TEG effective properties. For a given TEG, the net output power was less sensitive to changes in fin thickness than in fin spacing. The optimal heat sink designs predicted by the model for the cases studied had fin thicknesses of 0.32 and 0.44 mm with fin-to-fin distances of 1 mm.

Experimental investigation and performance evaluation of an oval tubular solar still with phase change material

The problem of freshwater scarcity is a major issue for people all over the world. Solar still is one of the most simplest and affordable ways to produce freshwater using solar energy which is available with no cost and eco-friendly. Recently, tubular solar stills (TSS) have gained popularity as one of the best solutions for acquiring pure water, especially in arid and coastal areas. The main objective of this paper is to enhance the productivity and efficiency of TSS by introducing a new form/shape, the oval tubular solar still (OTSS), integrated with cover cooling and phase change material (PCM). The OTSS is made of a transparent oval tube that is permeable to sunlight from all directions to maximize solar irradiance, and it is integrated with a black basin to improve absorption and water evaporation. It has an appropriate level of flexibility, durability, and low cost. Experiments were conducted out in the climatic conditions of Cairo, Egypt. This paper investigated different basin water depths and different water cover cooling flow rates to obtain their optimal values. Moreover, the effects of using PCM as a thermal management solution were studied in detail. In the case of no cooling, it is observed that the production rate decreases with increasing the water depth in the basin and the maximum production rate reached up to 5.21 L/m2/day at the optimal water depth of 0.5 cm. However, with cooling, the maximum production rate of 6.34 L/m2/day was achieved at the optimum water-cooling flow rate of 2 L/h. Using the PCM the maximum production rate of 6.78 L/m2/day was able to be achieved. The efficiency and productivity of the OTSS were enhanced by 41.26 % and 32.42 %, respectively, when using PCM. Furthermore, the daily thermal exergy efficiency of the OTSS was 3.46 %, 3.85 %, and 4.14 % for the cases no cooling, with cooling and with PCM, respectively. Economically, the cost per liter of desalinated water production was $0.020, $0.017, and $0.017 for the three cases, respectively.

Numerical study of water cooling jacket of a diesel engine using coupled field analysis

The engine is the ‘heart’ of the vehicle. The heat energy generated by the combustion of fuel is converted into mechanical work by an engine. Optimum operating temperature of an engine is one of the important parameters behind an engine’s performance. So, the main function of the engine cooling system is to control the normal operating temperature of the engine. The 3DExperience platform is used in the present work to conduct coupled field analysis on a 4-cylinder diesel engine. On this model, initially ‘CFD and Thermal coupled analysis’ was performed and outcomes were observed for the input boundary conditions. To increase the cooling performance of jackets, the concept of ‘Design of experiment’ is used. For that purpose, the ‘Latin hypercube DoE’ technique, which is particularly well-liked among many DoE techniques, is used. For 10 different design points, the results are obtained by varying the values of input parameter such as mass flow rate of coolant and inlet coolant temperature. We finalized values of input parameters for which we got the maximum cooling performance. Structural analysis was carried out to find the stresses and displacement for the above input parameters. Results of ‘Structural analysis’ showed that the maximum displacement and maximum von mises stress generated within model were well below than the permissible limits.

Effect of Coolant Temperature on the Thermal Compensation of a Machine Tool

Machine tool (MT) accuracy is an important factor in the industry and is affected by heat generation through internal and external moving parts; the electrical components used; and variable environmental temperatures. Thermal errors lead to 40–60% of all MT errors. To improve MT accuracy, efficient techniques to minimize thermal errors must be identified. This study investigated the coolant temperature effects under different rotating speeds of a standalone built-in spindle system and computer numerical control (CNC) machine with a direct-drive spindle on the accuracy of thermal deformation prediction. The z-axis thermal deformation of the standalone built-in spindle system and CNC machine with a direct-drive spindle was conducted at different spindle rotating speeds and coolant temperatures at a constant coolant flow rate of 5 LPM. All experiments were conducted in a steady and dynamic operation according to ISO 230-3. For the standalone built-in spindle system, in comparison to the Mares model, the developed new model based on the coolant temperature effect on the Mares model (Mares CT model) can improve the thermal deformation prediction accuracy by 18.17% to 39.50% at different coolant temperatures of 12 ∘C to 26 ∘C and the accuracy can be controlled within the range of 0.03 μm to 5.24 μm, while the supply coolant temperature is above 16 ∘C. However, the thermal compensation analysis of the Mares CT model for a CNC machine with a direct-drive spindle shows a thermal deformation prediction accuracy improvement of 58.30% to 66.35% at different coolant temperatures of 22 ∘C to 28 ∘C and the accuracy can be controlled within the range of 0.14 μm to 4.05 μm. To validate the feasibility of the compensation model in real machining processes, dynamic operational analysis was performed for a standalone built-in spindle system and a CNC machine with a direct-drive spindle, and the thermal deformation prediction accuracy improved by 12.19% to 35.53% with the standalone built-in spindle system and 40.25% to 60.33% with the CNC machine with a direct-drive spindle. The compensation model analysis shows that the coolant temperature has a high impact on thermal deformation prediction and markedly affects system accuracy within certain limits.