Numerical study of the Maisotsenko cycle heat and mass exchanger (original) (raw)
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Energy Conversion and Management, 2015
This report describes numerical modelling of heat and mass transfer in exchangers utilizing the Maisotsenko Cycle for indirect evaporative cooling. For this purpose, numerical models are developed based on the modified ε-NTU method to perform thermal calculations of the indirect evaporative cooling process, thus quantifying overall performance of considered heat exchangers. Numerical simulation reveals many unique features of considered HMX (heat and mass exchanger), enabling an accurate prediction of its performance. The results of computer simulation showed high efficiency gains that are sensitive to various inlet conditions, and allow for estimation of optimum operating conditions, including suitable climatic zones for the proposed unit using.
International Journal of Energy for a Clean Environment, 2011
porative cooling process, thus quantifying overall heat exchanger performance. This mathematical model accounts for many unique features of the cross-flow heat exchanger, enabling an accurate prediction of performance. Results of the model show high efficiency gains that are sensitive to various inlet conditions and allow for estimation of optimum operating conditions, including suitable climatic zones for the proposed unit.
International Journal of Heat and Mass Transfer, 2015
This paper investigates a mathematical simulation of the heat and mass transfer in the two different Maisotsenko Cycle (M-Cycle) heat and mass exchangers used for the indirect evaporative cooling in different air-conditioning systems. A two-dimensional heat and mass transfer model is developed to perform the thermal calculations of the indirect evaporative cooling process, thus quantifying the overall heat exchangers' performance. The mathematical model was validated against the experimental data. Numerical simulations reveal many unique features of the considered units, enabling an accurate prediction of their performance. Results of the model allow for comparison of the two types of heat exchangers in different applications for air conditioning systems in order to obtain optimal efficiency.
Energy, 2014
In this paper a novel cross-flow HMX (heat and mass exchanger) utilizing the M-cycle (Maisotsenko cycle) for dew point indirect evaporative cooling has been tested for the performance evaluation in terms of thermal effectiveness and specific cooling capacity under various ambient and operational conditions. Additionally, the operational performance of the investigated HMX was examined on the base of developed model. The obtained results from the model prediction have been compared with the experimental data. The positive results of this validation indicated that the proposed model may be successfully used for prediction of operational performance of the investigated HMX. The analysis presented in this paper further demonstrates attractiveness and high efficiency of the novel M-cycle HMX used for indirect evaporative cooling in air conditioning units.
Energy and Buildings, 2015
A mathematical simulation of the carefully selected geometrical and operational aspects of the cross-flow Maisotsenko cycle heat and mass exchanger used for indirect evaporative air cooling is investigated. A two-dimensional heat and mass transfer model is developed to perform thermal calculations of the indirect evaporative cooling process. Presented numerical model was validated against experimental data. Simulations bring out unique features of the considered heat and mass exchanger and allow finding which of the selected geometrical and operational aspects (extending the dry working air part at fixed primary part size, increasing secondary air part at cost of a primary part, operating the HMX under uneven air flow distribution) have more significant impact on its performance. Simulation was performed for two operational conditions: variable inlet temperature and variable inlet air flow rate.
Numerical analysis of selected evaporative exchangers with the Maisotsenko cycle
Energy Conversion and Management, 2014
This paper describes numerical modeling of heat and mass transfer in five different exchangers utilizing the Maisotsenko cycle for indirect evaporative cooling. For this purpose, numerical models are developed based on the modified e-NTU method to perform thermal calculations of the indirect evaporative cooling process, thus quantifying overall performance of considered heat exchangers. Numerical simulation reveals many unique features of considered devices, enabling an accurate prediction of their performance. The results of computer simulation showed high efficiency gains that are sensitive to various inlet conditions, and allow for estimation of optimum operating conditions, including suitable climatic zones for the proposed unit using.
Engineering Applications of Computational Fluid Mechanics , 2020
In this work, a numerical and experimental study is performed to evaluate the affecting variables on energy efficiency of a novel regenerative evaporative cooler utilizing dew-point indirect evaporative cooling. For first time, an investigation is experimentally and numerically carried out to study the effects of the channel number on important parameters such as product temperature and humidity ratio. Investigations are carried out for five configurations with various channel numbers. The comparison of the numerical and experimental results is obtained and well accuracy observed. For the five studied configurations, the results show that with an increase in the number of channels, the outlet temperature decreases. For an inlet air flow rate of 100–600m3/h, the cooled outlet flow temperature changes to the range of 23.4–30.7°C, 19.7–28.3°C, 18–26.4°C, 17.2–25°C and 16.6–23.8°C. For the configurations with finned channels, the percentage of increase in produced air temperature reaches 11.5% for HMX B, 18.6% for HMX C, 23.4% for HMX D and 26.9% for HMX E, as compared with HMX A.
E3S Web of Conferences
This paper presents results of mathematical simulation of the heat and mass transfer in the two different Maisotsenko Cycle (M-Cycle) heat and mass exchangers used for the indirect evaporative cooling in different airconditioning systems. A two-dimensional heat and mass transfer model is developed to perform the thermal calculations of the indirect evaporative cooling process, thus quantifying the overall heat exchangers' performance. The mathematical model was validated against the experimental data. Numerical simulations reveal many unique features of the considered units, enabling an accurate prediction of their performance. Results of the model allow for comparison of the two types of heat exchangers in different applications for air conditioning systems in order to obtain optimal efficiency.
Numerical study of a M-cycle cross-flow heat exchanger for indirect evaporative cooling
Building and Environment, 2011
In this paper, numerical analyses of the thermal performance of an indirect evaporative air cooler incorporating a M-cycle cross-flow heat exchanger has been carried out. The numerical model was established from solving the coupled governing equations for heat and mass transfer between the product and working air, using the finite-element method. The model was developed using the EES (Engineering Equation Solver) environment and validated by published experimental data. Correlation between the cooling (wet-bulb) effectiveness, system COP and a number of air flow/exchanger parameters was developed. It is found that lower channel air velocity, lower inlet air relative humidity, and higher working-to-product air ratio yielded higher cooling effectiveness. The recommended average air velocities in dry and wet channels should not be greater than 1.77 m/s and 0.7 m/s, respectively. The optimum flow ratio of working-to-product air for this cooler is 50%. The channel geometric sizes, i.e. channel length and height, also impose significant impact to system performance. Longer channel length and smaller channel height contribute to increase of the system cooling effectiveness but lead to reduced system COP. The recommend channel height is 4 mm and the dimensionless channel length, i.e., ratio of the channel length to height, should be in the range 100 to 300. Numerical study results indicated that this new type of M-cycle heat and mass exchanger can achieve 16.7% higher cooling effectiveness compared with the conventional cross-flow heat and mass exchanger for the indirect evaporative cooler. The model of this kind is new and not yet reported in literatures. The results of the study help with design and performance analyses of such a new type of indirect evaporative air cooler, and in further, help increasing market rating of the technology within building air conditioning sector, which is currently dominated by the conventional compression refrigeration technology.
Theoretical study of the basic cycles for indirect evaporative air cooling
International Journal of Heat and Mass Transfer, 2015
This paper presents a numerical study of heat and mass transfer in indirect evaporative air coolers with four air flow patterns: parallel-flow, counter-flow, cross-flow and regenerative. The numerical simulation was performed on the basis of original two-dimensional heat and mass transfer models (in the case of cross-flow heat exchanger the model was 3D). The mathematical models developed were validated against published experimental data presented in Appendix A. It was established, that heat and mass transfer processes in the wet channels of counter-flow, cross-flow and regenerative indirect evaporative coolers are characterized by creation of two particular heat and mass transfer zones. Detail analysis of the temperature and humidity ratio distributions and boundary conditions, characterizing the coupled heat and mass transfer process in each of these determined zones, revels the violation of the Lewis relation unity under a certain inlet and operation conditions. A theoretical method for estimating the Lewis factor was proposed. Using the developed models the thermal performances of the conventional designs of indirect evaporative air coolers were analyzed numerically and preferable climatic zones for considered heat exchanger were established. Four novel heat exchangers utilizing the advantages of the basic cycles heat exchangers were presented.