Енергоощадний режим роботи ректифікаційної колони зневоднення етиленгліколю

Systematic Analysis Reveals Thermal Separations Are Not Necessarily Most Energy Intensive

The method of determination of optimal working conditions of vertical ground heat exchanger for heat pump low temperature water heating system, providing minimum energy cost for heat production is presented in this article. It was determined that there is an optimum speed of a heat carrier to which minimum total cost of electricity for heating system in a whole corresponds when using vertical probes for heat pump heating system. The correlation between the characteristics of vertical ground heat exchanger (depth of the well, the intensity of selection of heat from the soil pipe diameter, the velocity of a heat carrier) in its optimal working conditions was found. It is shown that the optimum speed of a heat carrier in the lower circuit and relevant hydraulic loss depends on the depth of the well, the heat exchanger tube diameter and type of ground, weakly depend on the thermal characteristics of a heat carrier and are almost independent of temperature conditions of heat pump systems. The determined correlations for vertical ground heat exchanger characteristics can be used at the design stage of heat pump heating systems using ground heat for ensuring their maximum energy efficiency. thermal characteristics of a heat carrier and are almost independent of temperature conditions of heat pump systems. The determined correlations for vertical ground heat exchanger characteristics can be used at the design stage of heat pump heating systems using ground heat for ensuring their maximum energy efficiency.

Highly sensitive microfluidic strain sensors with low hysteresis using a binary mixture of ionic liquid and ethylene glycol

Operational and economic feasibility of different heat-pump systems with mechanical compression integrated to real batch distillation columns are investigated. This study is focused to the reduction of the external energy demand of the batch distillation. The separation of a low relative volatility mixture (n-heptane-toluene) is studied by rigorous simulation performed with a professional dynamic flow-sheet simulator. The distillation column has AE-1000 reactor-reboiler of DIN standard type. The methods studied are vapour recompression, vapour compression and vapour recompression with the application of an external heat exchanger. Operational, heat transfer and economic issues are discussed. We stated that for the VRC in the minimal pay-pack period point the operation time of the batch process is significantly higher (the production capacity is much lower) than that of the conventional batch distillation. For boosting the overall performance of the VC system, we suggested to complete it with an external heat exchanger (VRC-E) where the heat of the compressed top vapour is transferred to the usual heating medium (water). The original VRC system was not economical (payback period much above 10 y). However the payback period of the new VRC-E system was significantly shorter (less than 10 y).

Chapter 10 Pinch point analysis

In terms of the separation of an ideal binary mixture of hypothetical components A and B, the synthesis and design of the externally heat‐integrated double distillation columns (EHIDDiC) are studied under the assumption of a constant pressure elevation from the low‐pressure (LP) to the high‐pressure (HP) distillation columns involved. It is found that employing one to three external heat exchangers can be a reasonable design option for the EHIDDiC. When multiple external heat exchangers (e.g. more than three external heat exchangers) have been adopted, the process configuration must be carefully determined because the increase in the number of stages externally heat‐integrated might not necessarily be beneficial to the system performance in this situation. This phenomenon has been caused by the strong mass and heat coupling between the HP and LP distillation columns involved and reflects also the unique characteristic of the EHIDDiC. For the reduction of capital investment, the total external heat exchange areas should be installed through as small a number of heat exchangers as possible and the extreme situation comes to the employment of a single external heat exchanger, thereby requiring subtle wisdom in arranging the total heat transfer areas between the HP and LP distillation columns involved. These insightful findings are of great significance to process synthesis and design. In addition, a novel decentralized control scheme is proposed for the operation of the EHIDDiC. Copyright © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.

An energy cost reduction study of the Midwest Grain Products, Atchison, Kansas Beverage grade alcohol (from grain) and speciality starch plant has been completed. The objective was to find out effective energy cost reduction projects and to develop a coherent strategy for realizing the savings. There are many possible options for reducing energy cost. To facilitate a fair comparison of the options, Pinch Technology was used to identify appropriate heat recovery, heat pumping and cogeneration options. Of particular interest were the opportunities for utilizing heat pumps, for energy cost reduction or other profit increasing uses. Therefore, where a heat pumping scheme was identified, its merits relative to other potential projects was carefully evaluated to ensure that the heat pump was technically and economically sound. It is felt that the results obtained in this study are applicable to other alcohol plants, due to the similarity of processes throughout the industry. This study and others indicate that reductions in thermal energy consumption of 10--30% can be expected through increased heat recovery. Additional energy cost reductions can be achieved through the use of MVR evaporators and other heat pump systems. 16 figs., 3 tabs.

An energy cost reduction study of the American Fructose Decatur,Inc. High Fructose Corn Syrup process has been completed. The objective was to find cost effective energy cost reduction projects and to develop a coherent strategy for realizing the savings. There are many possible options for reducing energy cost. To facilitate a fair comparison of the options, Pinch Technology was used to identify appropriate heat recovery, heat pumping and cogeneration options. Of particular interest were the opportunities for utilizing heat pumps, for energy cost reduction or other profit increasing uses. Therefore, where a heat pumping scheme was identified, its merits relative to other potential projects was carefully evaluated to ensure that the heat pump was technically and economically sound. It is felt that the results obtained in this study are applicable to other wet corn milling sites which include a refinery section, due to the similarity of processes throughout the industry. This study and others indicate that reductions in thermal energy consumption of 15--25% can be expected through increased heat recovery. Also, the use of MVR and thermocompression evaporators is appropriate and additional economically viable opportunities exist for using industrial heat pumps to increase even further the level of energy cost reduction achievable. 17 figs., 4 tabs.

Optimal configuration of ternary distillation columns using heat integration with external heat exchangers

Electric vehicle heat pumps are drawing more and more attention due to their energy-saving and high efficiency designs. Some problems remain, however, in the usage of the heat pumps in electric vehicles, such as a drainage problem regarding the external heat exchangers while in heat pump mode, and the decrease in heating performance when operated in a cold climate. In this article, an R134a economized vapor injection (EVI) heat pump system was built and tested. The drainage problem common amongst external heat exchangers was solved by an optimized 5 mm diameter tube-and-fin heat exchanger, which can meet both the needs of a condenser and evaporator based on simulation and test results. The EVI system was also tested under several ambient temperatures. It was found that the EVI was a benefit to the system heating capacity. Under a −20 °C ambient temperature, an average improvement of 57.7% in heating capacity was achieved with EVI and the maximum capacity was 2097 W, with a coefficient of performance (COP) of 1.25. The influences of injection pressure and economizer capacity are also discussed in this article.

The method of determination of optimal working conditions of vertical ground heat exchanger for heat pump low temperature water heating system, providing minimum energy cost for heat production is presented in this article. It was determined that there is an optimum speed of a heat carrier to which minimum total cost of electricity for heating system in a whole corresponds when using vertical probes for heat pump heating system. The correlation between the characteristics of vertical ground heat exchanger (depth of the well, the intensity of selection of heat from the soil pipe diameter, the velocity of a heat carrier) in its optimal working conditions was found. It is shown that the optimum velocity of a heat carrier in the lower circuit depends on the depth of the well, the heat exchanger tube diameter, and is almost independent of temperature conditions works of heat pump systems. It is found that the higher velocity observed at the beginning of the heating period in view of energy storage in the ground. Optimum coolant velocity should decrease until the end of the heating season to ensure minimum specific energy expenditure at HPS. Also noted that an optimum velocity increases with increasing depth of the well and with decreasing diameter of the heat exchanger tube. The established correlation may be used when determining the optimum operating conditions of the vertical ground heat pump heat exchanger low-temperature heating systems with a plan to maximize their energy efficiency. Bibl. 8, Fig. 7.

The paper provides the reducing method efficiency assessment of the heat losses into the environment due to the heat losses supply to the heat carrier flow, previously flowing through the additional water jacket including the subsequent heated heat carrier flow direction into the heat-exchanging unit main flow part. Accordingly, the main heat carrier is notionally considered as the «active» insulation. The theoretical comparative analysis of this type of insulation efficiency with regard to the modes typical for the MCU recovery systems was conducted. The study was carried out by means of the numerical method through the heat transfer processes modelling of the system «heat carrier – wall – hot gas – wall – heat carrier - environment», i.e. in the recuperative heat exchanger possible design simplified version. Thus, the comparative study and analysis subject is the design consisting in the first case of two coaxial tubes, between which the hot gas flows (internal combustion engine exhaust gases) and water flows through the axial channel, while in the second case – of three coaxial tubes with the main heat carrier (water) flowing through the axial and external circular channels. In the second case, the water mass flow rate of the external circular and internal cylindrical channels is the same. The heat transfer processes calculation analysis was conducted on the basis of the convective heat transfer, thermal conductivity and radiation heat transfer known equations implemented in the ANSYS software.

Owing to the prevailing escalation in energy costs, escalating energy demands, depletion of conventional resources, and escalating greenhouse gas emissions, there has been an expeditious upsurge in the worldwide proliferation of alternative energy sources. Geothermal systems, in particular, are highly coveted as environmentally friendly and sustainable renewable energy reservoirs, offering efficacious cooling and heating capabilities for various structures (Xu et al., 2020; Ghasemi-Fare & Basu, 2013). The energy exchange efficiency of geothermal systems is significantly contingent upon the ground temperature, enabling the discharge of energy into the ground for cooling purposes in summer and its retrieval for heating requirements during winter. However, long-term operation of geothermal energy systems can engender an imbalance in thermal recovery through the heating and cooling processes, consequently influencing the thermomechanical behavior of the subsurface over time (Baek et al., 2017). Geothermal systems, also known as ground source heat pumps (GSHPs), are designed to operate for around 20 years, while the heat source component can be utilized for an extended duration ranging from 30 to 50 years. Understanding heat transfer characteristics and long-term performance of geothermal energy systems is crucial for optimal utilization and efficiency. However, research often lacks field investigation data, specifically for long-term monitoring and validation of fluid temperatures and subsurface temperature profiles. This research conducted comprehensive long-term measurements to assess fluid and subsurface temperature behavior in a borehole heat exchanger (BHE) system. The study examined the impact of sustained BHE performance on surface and subsurface temperature dynamics. A sophisticated three-dimensional numerical model was developed based on empirical insights from the field study and validated using monitored data. The analysis included inlet/outlet fluid temperature, spatial heterogeneity of ground temperature profiles, thermal recovery processes, and alterations caused by residual thermal energy.
 Furthermore, additional temperature sensors were deployed at various depths to monitor temperature changes at distinct levels within the subground.
 In this study, an advanced three-dimensional (3D) numerical model was developed utilizing the Finite Element Method (FEM) to effectively capture the intricate heat transfer processes occurring around BHEs. The geometry mesh was generated using a specialized triangular mesh generator, enabling spatial variation of element sizes to accurately represent the geometry and temperature distribution patterns. To address the specific requirements of U-tube heat exchanger loops, where the steepest temperature gradient is anticipated, a meticulously chosen element size of 0.7 mm, was employed. As the model extends towards the lateral boundaries, particularly in the radial direction, the element size gradually increases to ensure faithful representation of the system's characteristics. To properly account for diverse vertical temperature gradients, the number of elements and the vertical distance between slices were systematically adjusted within a range of 0.01 to 5 m. This meticulous variation facilitated accurate consideration of the distinct vertical temperature profiles. Notably, the finest discretization was applied near the bottom of the BHE (approximately z = -155 m) and at the top surface, characterized by a significant temperature gradient.
 The depicted Figure 2 showcases the model's performance in analyzing the fluid profile in comparison to the monitored data over a duration of 600 hours. This comparison reveals that the maximum relative difference between the monitored and simulated values for the inlet and outlet fluid temperature does not exceed 2.649 and 2.296 degrees Celsius, respectively. These findings offer compelling evidence of the exceptional accuracy of the proposed numerical modeling approach, thus affirming its suitability for examining the long-term sustainability of BHE systems.

Large energy costs for the process of drying grain crops associated with the increase in the price of energy carriers pose the task of reducing the energy component to the developers. The presented article focuses on the development of measures to reduce energy costs for the grain drying process using heat pumps. The considered advantages of heat pumps indicate the possibility of using these units for drying grain crops. Especially noteworthy is the increase in energy efficiency of heat pumps due to the conversion of ambient heat with a low temperature potential into heat with a high temperature potential. Thus, heat pumps are characterized by the heat pump conversion factor, which indicates their efficiency. The presented schemes with a heat pump implement the drying process in convective dryers, in particular in chamber, tunnel, shaft and drum dryers. Different schemes of heat pumps can be used for different types of dryers. The use of alternative drying sources for grain drying, in particular solar energy in the heat pump system, dramatically increases the efficiency of this installation. Also presented is a comprehensive scheme for the utilization of spent coolant in heat exchangers, an economizer, and a heat pump, which comprehensively addresses the issue of coolant utilization in a chamber dryer. In the drum dryer, the utilization of the spent coolant in heat exchangers and a heat pump is provided, increasing the temperature of the drying agent at the entrance to the dryer. For drying plant raw materials in a two-zone tunnel dryer, a heat pump scheme with two temperature levels of the heat carrier was developed for drying the material at different temperatures in the dryer zones.

In the present study, the relevance of microclimate considerations in the residential premises of high-rise buildings is considered. The application of a natural exhaust ventilation system without forced air removal leads to a deterioration in the quality of the indoor air environment, including suboptimal temperature and humidity conditions, an increase in CO2 and dust concentration, as well as the development of pathogenic microorganisms. A transition from a natural ventilation system to one using air recuperative heat exchangers to reuse recyclable heat is proposed. In conditions of low winter temperatures, the prob-lem of freezing in plate heat exchangers leads to a decrease in their energy efficiency. The main content of the study for the operating air supply and exhaust unit with a plate recuperator involves an analysis of methods for preventing freezing and a comparative calculation of energy costs. Three options for pre-venting freezing are considered: the use of an electric air heater prior to the recuperator for heating air to -14 ºC (the freezing condition for this heat exchanger); the use of a bypass to defrost the heat exchanger; the use of a heat pump to transfer heat energy from the exhaust to the supply air. In the developed ex-perimental model with a heat pump, Freon R410A is used as a heat carrier. The calculated data indicate the total energy consumption at -36 ºC to comprise 20.4, 21.3 and 13.5 kW when using an electric air heater, a recuperator with a bypass and a heat pump, respectively. Additionally, the dependences of the change in relative humidity on temperature are derived. Summarising the obtained results, it is possible to use a heat pump for rationalising thermal and electric energy spent on building heating and maintain-ing the indoor microclimate.