Cold Water Inlet Temperatures Research Articles

Experimental study on top liquid-cooling thermal management system based on Z-shaped micro heat pipe array

The traditional bottom liquid-cooling thermal management system (TMS) has poor cooling performance and is prone to causing significant temperature difference in the lithium-ion battery (LIB) module. In order to solve the above problems, this study takes the Z-shaped micro heat pipe array (MHPA) as the core heat transfer element and establishes a top liquid-cooling (TLC) TMS based on Z-shaped MHPA. The thermal management performance of the TLC TMS based on Z-shaped MHPA is analyzed by comparing it with the traditional bottom liquid-cooling TMS. Results show that under the conditions of 40 °C ambient temperature and 25 °C cold water inlet temperature, the bottom liquid-cooling TMS can no longer meet the thermal management requirements of the module at a 2C charge–discharge rate. In comparison, the TLC TMS based on Z-shaped MHPA can ensure the module's maximum temperature below 55 °C, and the battery and module level's temperature difference can be controlled below 4 °C under 3C charge–discharge rate. The TLC TMS based on Z-shaped MHPA can not only effectively delay the battery's temperature rise under high charge–discharge rate, but also significantly reduce the temperature difference; its thermal management performance is significantly better than the bottom liquid-cooling TMS.

Experimental Study of Double Pipe Helical Coil Heat Exchangers in the Laminar to Transitional Flow Regime

This study experimentally investigates various heat transfer characteristics, pressure drop, friction factor, Nusselt number, and Dean Number in a double-pipe helical coil heat exchanger. The study examines the hot water mass flow rates ranging from 0.02 to 0.12 kg/s and the cold-water mass flow rates ranging from 0.055 to 0.15 kg/s. The cold-water inlet temperature was maintained at 29°C, while the hot water inlet temperature varied between 65-75°C. Based on the hydraulic diameter of the annular space between the two tubes, the Reynolds number ranged from 1000-6000. All required parameters, such as the inlet and outlet temperatures of the inner coil and annulus fluids and the flow rate of fluids, were measured using appropriate instruments. Seventy-two test runs were conducted, from which the heat transfer coefficients of the inner coil side and annulus side were calculated. The calculated heat transfer coefficients of the inner coil were compared with available correlations from the literature, and a reasonable agreement was found.

Experimental study on the bottom liquid cooling thermal management system for lithium-ion battery based on multichannel flat tube

Thermal management system (TMS) plays an important role in reducing the battery module’s temperature rise and ensuring temperature uniformity. In this study, a bottom liquid cooling (BLC) TMS based on multichannel flat tube (MCFT) is established. The temperature distribution of the battery module under the BLC method is analyzed through comparative experiments with the passive cooling method. Then, the influence of cold water flow rate and cold water inlet temperature variation on thermal management performance are studied. Results show that the BLC TMS based on MCFT can effectively reduce the temperature rise of the battery module without considerably reducing the temperature uniformity of the module. The increase in the cold water flow rate slightly influences the thermal management performance of the battery module, the change in the module’s maximum temperature is only 1.4%. However, the change in the cold water inlet temperature considerably influences the thermal management performance of the battery module. The temperature of the battery module can be maintained below 45 °C by decreasing the cold water inlet temperature, but the temperature difference of the battery and module levels are increased by 48.9% and 61.6%, respectively.

Investigations on tube in tube metal foam heat exchanger

The heat transfer equipments with higher heat transfer ability are needed in several industrial applications. With conventional methods, size of the device increases and it becomes bulky. With the use of metal foam, it is possible to attain large ratios of surface to volume. Therefore, using metal foam in heat exchanging devices is crucial. The main reason behind the use of metal foam over conventional method is its weight-saving and impact-absorbing structures. Insertion of metal foam in heat exchangers for various applications can lead to greater effectiveness and heat transfer enhancement. It has been observed that very few researchers have participated in the area of double tube heat exchangers (DTHE) having annular spaces filled with metal foam. The present work deals with numerical and CFD analysis of double tube heat exchanger (DTHE) with metal foam having different pore densities differing from 10 PPI to 50 PPI & performance evaluation of the same by taking hot water stream and cold water stream as working fluids. The modelling was created in Creo & simulation was done with k-omega (2 equation) viscous model in Ansys fluent flow. In the present work, double tube heat exchanger was considered in counter flow mode with inner sided tube (Stainless Steel) ID 9.5 mm & OD 12.7 mm and outer sided tube (Galvanized Iron) ID 28 mm & OD 33.8 mm. For fully developed turbulent flow, total length was considered as 1.5 m. The water streams through inner tube and annular space were flowing at uniform and constant flow rates of 2 lpm and 10 lpm respectively. Hot water and cold water inlet temperatures were taken at 800c & 300c respectively. For the analysis nickel metal foam with 10 PPI to 50 PPI with 0.9 porosity was inserted in the annular spaces of DTHE. For different pore densities comparative analysis was done. It was found that with rise in pore density of metal foam heat transfer rate (HTC) and pressure drop increased for both numerical & mathematical results. CFD simulation results were in good agreement with results obtained from empirical correlations taken from literature.

PERFORMANCE OPTIMIZATION OF COUNTER FLOW DOUBLE PIPE HEAT EXCHANGER USING GREY RELATIONAL ANALYSIS

Among various classifications of the heat exchanger, counter flow double pipe heat exchanger (CF-DPHE) is more suitable for many industrial heat transfer applications. In general, numerous research works are carried out to find optimal operating parameters for heat exchangers. In this study, grey relational analysis (GRA) is used to optimize the heat exchanger system output parameters such as the cold water outlet temperature (t2), the hot water outlet temperature (T2) and the effectiveness (ϵ). Such output parameters are the functions of the mass flow rate of cold fluid (mc), cold water inlet temperature (t1), the mass flow rate of hot fluid (mh), and hot water inlet temperature (T1). The application of this GRA method is capable of increasing counter flow double pipe heat exchanger effectiveness by 12.06%.

Exergy analysis of Shell and helical coil heat exchanger and design optimization

In this study, experimental investigations and exergy analysis on shell and helically coiled tube heat exchanger are carried out for free convection heat transfer. The measured data are totally optimised utilizing thermodynamics rules in which exergy study is performed to investigate the thermal performance of the helical system under different operating conditions. The experimental set-up of apparatus are designed and made for cold water and hot water as a working fluid of both the shell side and helical coil side, respectively. The effects of several parameters such as geometry and operational conditions on the exergy destruction and dimensionless exergy destruction are investigated. The counter flow direction is considered under the steady state flow condition, and the critical Reynolds number was more than 4000 in this study. The main objective of this work was to clarify the effect of the volume flow rates and inlet temperatures of hot water and cold water in the shell and helical coil on exergy efficiency and pressure drop. Results showed that the exergy destruction and dimensionless exergy destruction decrease with the increase of coil pitch and Dean number. In contrast, the exergy destruction and dimensionless exergy destruction are obviously increased with the hot water flow rates or cold water flow rates. These exergy characteristics are also augmented with the values of hot water inlet temperatures and cold water inlet temperatures. The pressure drop is considerably increased with the increase of Dean number and reduced with the increase of coil diameter. While, the exergy efficiency steadily increases with the decrease of the cold water flow rates and with the increase of Dean number.

Multi drain heat recovery system – Thermal modeling, parametric analysis, and case study

The present work concerns parametric analysis and case study of the performance of a newly suggested Multi Drain Heat Recovery System (MDHRS) that uses the relatively hot water of different drain sources such as the shower, the dish washer, the washing machine, and the sink simultaneously to heat/preheat residential cold water. To proceed, an appropriate thermal modeling along with its associated in-house code are developed. The heat rate error between numerical and experimental results is always below 14.2% for different inlet cold water temperatures and for different cold and hot water flow rates. The parametric analysis performed treated the effect of the hot and cold water inlet temperatures and flow rates on the performance of the system and allowed to raise practical recommendations in terms of application of the suggested concept. In the case study presented, the monthly amount of energy reduced, the monthly amount of money saved and the monthly amount of CO2 emissions reduction are considered. It was shown that when the heat exchanger length increases from 0.2 m to 1 m, the monthly amount of reduced energy increases from 102.2 kWh to 410.9 kWh, the monthly amount of money saved increases from 13.3 $ to 53.4 $ and the monthly amount of emissions reduction increases from 72.5 kg to 291.7 kg for a drain water temperature of 25 °C for the case of Lebanon.

Design, Fabrication and Performance Evaluation of a Shell and Tube Heat Exchanger for Practical Application

A heat exchanger is a device used to transfer thermal energy between two or more fluids, at different temperatures in thermal contact. This paper focuses on a shell-and-tubes heat exchanger that involves two fluids (hot water and cold water) in contact with each other while the cold water flows through the tubes and hot water through the shell. Heat exchangers have special and practical applications in the feed water cooler in the process industries, power plants, chemical plants, refineries, process applications as well as refrigeration and air conditioning industry. The design calculations were carried out to determine the specifications of essential parameters for the development of the heat exchanger, data generated from the theoretical formulae were used to fabricate the heat exchanger using some locally available and durable materials, and the performance of the system was evaluated. Some of the parameters evaluated include heat duty, capacity ratio, effectiveness, overall heat transfer coefficient, and fouling factor. The heat exchanger was tested under various flow conditions and the results obtained were as follows; cold water inlet temperatures of (26, 26, 26, 27and 27) ºC increased to (59, 44, 39, 47 and 35) ºC after (10, 7½, 6½ 8, and 6) minutes and the hot water temperatures decreased from (100, 80, 75, 87 and 73) ºC to (73, 59, 55, 62 and 50) ºC, respectively. The design data and test data were compared in terms of the heat duty, capacity ratio, effectiveness, overall heat transfer coefficient, and fouling factor, the deviation is found to be 22.87%, 13.99%, 8.98%, 43.30%, and 43.30% respectively. The results obtained proved that the heat exchanger was effective, reliable and provides a good technical approach to evaluate the thermal performance of the heat exchanger and useful in conducting heat and mass transfer practical in thermodynamics laboratory.

Design, Fabrication and Performance Evaluation of a Shell and Tube Heat Exchanger for Practical Application

A heat exchanger is a device used to transfer thermal energy between two or more fluids, at different temperatures in thermal contact. This paper focuses on a shell-and-tubes heat exchanger that involves two fluids (hot water and cold water) in contact with each other while the cold water flows through the tubes and hot water through the shell. Heat exchangers have special and practical applications in the feed water cooler in the process industries, power plants, chemical plants, refineries, process applications as well as refrigeration and air conditioning industry. The design calculations were carried out to determine the specifications of essential parameters for the development of the heat exchanger, data generated from the theoretical formulae were used to fabricate the heat exchanger using some locally available and durable materials, and the performance of the system was evaluated. Some of the parameters evaluated include heat duty, capacity ratio, effectiveness, overall heat transfer coefficient, and fouling factor. The heat exchanger was tested under various flow conditions and the results obtained were as follows; cold water inlet temperatures of (26, 26, 26, 27and 27) ºC increased to (59, 44, 39, 47 and 35) ºC after (10, 7½, 6½ 8, and 6) minutes and the hot water temperatures decreased from (100, 80, 75, 87 and 73) ºC to (73, 59, 55, 62 and 50) ºC, respectively. The design data and test data were compared in terms of the heat duty, capacity ratio, effectiveness, overall heat transfer coefficient, and fouling factor, the deviation is found to be 22.87%, 13.99%, 8.98%, 43.30%, and 43.30% respectively. The results obtained proved that the heat exchanger was effective, reliable and provides a good technical approach to evaluate the thermal performance of the heat exchanger and useful in conducting heat and mass transfer practical in thermodynamics laboratory.

Simulation of Convection Flow and Sensitivity Analysis of Model Parameters of Evacuated Glass Tube Solar Water Heater

The water-in-glass evacuated collectors are made up of parallel circular tubes. They are installed with some inclination angle to the horizontal. The thermal performance of water-in-glass evacuated tube solar water heater heavily depends on weather conditions. The analysis of the sensitivity of the model parameter and weather conditions on heat transfer process is extremely important to install a solar water heater system in order to achieve its maximum efficiency. The evaluation of the sensitivity of the system parameters is done by considering one parameter after another while keeping the remaining fixed. Further to the analysis of the heat transfer process, the average heat transfer coefficient and the average natural circulation flow rate are calculated.
 The fluid flow is assumed to be unsteady, two-dimensional, laminar and incompressible. The heat and fluid flow are analyzed using the Navier-Stokes equations and temperature equation for an incompressible fluid, subject to density variation with temperature. The discretization of the governing equations is done by Finite Volume Method (FVM). The Open FOAM computational fluid dynamic software with PISO-SIMPLE algorithm is used for the simulation.
 The results show that the heat transfer process is improved when there is a moderate level inclination angle. Further, it is found that when the ratio of tube length to diameter is high, the heat transfer process is improved. The solar radiation input highly affects the performance of a solar water heater. The cold-water inlet temperature does not directly affect the buoyancy induced flow, but it influences the temperature gain.
 The angle of the solar rays vary within the daytime, however it does not affect the performance of the solar water heater since an evacuated-tube has a circular absorbing surface, it passively tracks the sun throughout the day. 
 These results recommend using moderate level tube inclination angle and high ratio to improve the performance of a solar water heater.

Combined energy and exergy analysis of a corrugated plate heat exchanger and experimental investigation

This paper presents an experimental investigation on combined energetic and exergetic performance characteristics of a corrugated plate heat exchanger using water. On the basis of experimental data considering heat exchange with ambient, various energetic and exergetic performance parameters have been evaluated and discussed their interrelationship. General relationship between energy effectiveness and exergy efficiency has been established as well. The result shows that the exergetic efficiency increases with the Reynolds number, hot and cold water inlet temperatures. The exergy loss increases with increase in hot side Reynolds number and inlet temperature, and decreases with increase in cold side Reynolds number and inlet temperature. The dimensionless exergy loss increases with increase of friction factor and number of transfer units. Study reveals that the heat loss has significant contribution on irreversibility and both heat capacity ratio and effectiveness affect the exergetic efficiency. Some energy–exergy relationship correlations have been also obtained based on experimental data.

Experimental studies on a closed cycle demonstration OTEC plant working on small temperature difference

Ocean thermal energy conversion (OTEC) technology utilizes the temperature difference between the warm surface water and deep coldwater of the ocean to operate a heat engine to generate electricity. An experimental study was carried out on a newly designed closed cycle demonstration OTEC plant with the help of temperature and pressure measurements before and after each component. An increase in the warm water temperature increases the heat transfer between the warm water and the working fluid, thus increasing the working fluid temperature, pressure, and enthalpy before the turbine. The performance is better at larger flowrates of the working fluid and the warm water. It is found that the thermal efficiency and the power output of the system both increase with increasing operating temperature difference (difference between warm and cold water inlet temperature). Increasing turbine inlet temperatures also increase the efficiency and the work done by the turbine. The efficiency and the power output increase with increasing ratio of warm water to coldwater flowrates. A maximum efficiency of about 1.5% was achieved in the system. The findings from this work can contribute to the development of OTEC technologies.

Experimental studies on a corrugated plate heat exchanger for small temperature difference applications

Experimental studies were performed on a corrugated plate heat exchanger for small temperature difference applications. Experiments were performed on a single corrugation pattern on 20 plates arranged parallelly, with a total heat transfer area of 1.16298 m 2. The spacing, Δ X, between the plates was varied (Δ X = 6 mm, 9 mm, and 12 mm) to experimentally determine the configuration that gives the optimum heat transfer. Water was used on both the hot and the cold channels with the flow being parallel and entering the heat exchanger from the bottom. The hot water flowrates were varied. The cold side flowrate and the hot and cold water inlet temperatures were kept constant. It is found that for a given Δ X, the average heat transfer between the two liquids increases with increasing hot water flowrates. The corrugations on the plates enhance turbulence at higher velocities, which improves the heat transfer. The optimum heat transfer between the two streams is obtained for the minimum spacing of Δ X = 6 mm. The pressure losses are found to increase with increasing flowrates. The overall heat transfer coefficients, U, the temperature difference between the two stream at outlet, and the thermal length are also presented for varying hot water flowrates and Δ X. The findings from this work would enhance the current knowledge in plate heat exchangers for small temperature difference applications and also help in the validation of CFD codes.