Design and Performance Investigation of a Compact Catalytic Reactor Integrated with Heat Recuperator

The catalytic combustion has the advantage of lower auto-ignition temperature and helps to expand the combustible limit of lean premixed gas. However, the intake needs to be preheated to certain temperature commonly through an independent heat exchanger. Similar to the principles of non-catalytic RTO combustion, this paper presents a similar approach whereby the combustion chamber is replaced by a catalytic combustion bed. A new catalytic reactor integrated with a heat recuperator is designed to enhance the heat recirculation effect. Using a two-dimensional computational fluid dynamics model, the performance of the reactor is studied. The reaction performances of the traditional and compact reactors are compared and analyzed. Under the same conditions, the compact reactor has better reaction performance and heat recirculation effect, which can effectively decrease the ignition temperature of feed gas. The influences of the inlet velocity, the inlet temperature, the methane concentration, and the thermal conductivity of porous media on the reaction performance of integrated catalytic reactor are studied. The results show that the inlet velocity, inlet temperature, methane concentration, and thermal conductivity of porous media materials have important effects on the reactor performance and heat recirculation effect, and the thermal conductivity of porous media materials has the most obvious influence. Moreover, the reaction performance of multiunit integrated catalytic reactor is studied. The results show that the regenerative effect of multiunit integrated catalytic reactor is further enhanced. This paper is of great significance to the recycling of low calorific value gas energy and relieving energy stress in the future.

Method of engineering calculation of recuperator parameters for heat extraction from tempered soybeans

In the conditions of constant growth of prices for consumed energy and competition in the domestic market, rural commodity producers have a problem to reduce energy costs, since they make up a significant share in the cost of agricultural products. There are particularly high energy costs in the heat treatment of meat and dairy products and grain. To reduce energy costs for thermal purposes, you can use the secondary heat extraction and its use in a specific technological process. To calculate the parameters of a heat recuperator that reuses heat energy from heat-treated soybeans, an engineering calculation method is presented.

Energy Balance of a Low Energy House with Building Structures with Active Heat Transfer Control

A qualitatively new dimension has been introduced to the issue of building structures for energy-efficient buildings by the system of Active Thermal Insulation (ATI), which is already applied in the construction of such buildings. ATI are embedded pipe systems in the envelope structures of buildings, into which we supply a heat-carrying medium with adjusted temperature, so this constitutes a combined building-energy system. This introduces the concept of an internal energy source understood as an energy system integrated into the zone between the static part and the thermal insulation part of the building structure envelope. Under certain conditions, the ATI can serve as a heat recuperator or as an energy collector for a heat pump application. ATI consists of pipe systems embedded in building structures, in which the medium circulates heated by energy from any heat source. The function of the system is to reduce or eliminate heat losses through non-transparent structures in the winter and at the same time to reduce or eliminate heat gains in the summer. It is especially recommended to apply heat sources using renewable energy sources due to the required low temperatures of the heating medium and thus shorten the heating period in the building. Also recommended is to apply ATI for the use of waste heat. Buildings with a given system show low energy consumption and therefore meet the requirements of Directive no. 2018/844/EU, according to which, from 01.01.2021, all new buildings for housing and civic amenities should have energy needs close to zero.

Supercritical CO2 Binary Mixtures for Recompression Brayton s-CO2 Power Cycles Coupled to Solar Thermal Energy Plants

In this work, an evaluation and quantification of the impact of using mixtures based on supercritical carbon dioxide “s-CO2” (s-CO2/COS, s-CO2/H2S, s-CO2/NH3, s-CO2/SO2) are made as a working fluid in simple and complex recompression Brayton s-CO2 power cycle configurations that have pressure drops in their components. These cycles are coupled with a solar thermal plant with parabolic-trough collector (PTC) technology. The methodology used in the calculation performance is to establish values of the heat recuperator total conductance (UAtotal) between 5 and 25 MW/K. The main conclusion of this work is that the cycle’s efficiency has improved due to using s-CO2 mixtures as working fluid; this is significant compared to the results obtained using the standard fluid (pure s-CO2). Furthermore, a techno-economic analysis is carried out that compares each configuration’s costs using pure s-CO2 and a mixture of s-CO2/COS with a molar fraction (70/30), respectively, as working fluid where relevant results are obtained. These results show that the best configuration in terms of thermal efficiency and cost is the RCC-RH for pure sCO2 with values of 41.25% and 2811 $/kWe, while for the mixture sCO2/COS, the RCC-2RH configuration with values of 45.05% and 2621 $/kWe is optimal. Using the mixture costs 6.75% less than if it is used the standard fluid (s-CO2).

COMPLEX APPROACH METHODOLOGY AT DESIGNING VENTILATING EQUIPMENT WITH HEAT RECUPERATOR FOR ENTERPRISES OF ENGINEERING INDUSTRY

There are problems unsettled by manufacturers and installers of ventilation equipment during the design and definition of economy of its use connected with the absence of taking into account specific peculiarities of conditions for its operation and definition of reliable initial data for designing that causes errors during designing and unjustified expectations of a customer. There are obtained analytical dependences allowing the definition of reliable initial data for designing ventilation equipment with the recuperator of the heat of air removed for the specific conditions of operation in an engineering workshop. On their basis there is developed an algorithm for the computation of money savings taking into account actual energy consumption in value terms while overcoming aerodynamic resistances, a technique for the automated choice of essential equipment is also shown. The problem of the theoretical definition of incoming air temperature at the output of the recuperator Tin. air re. is solved. For computation automation there is carried out an approximation of data by mean temperature Tatm during diurnal hours Tatm day and nocturnal ones Tnoct. of the day for the last ten years for the eastern areas of Belarus and regression equations are obtained. The algorithm obtained in combination with analytical dependences for the definition of the condensate volume formed in the recuperator at the efficient arrangement of the ventilation equipment make a methodology for the complex approach at designing ventilation equipment with the heat recuperator for enterprises of engineering industry. The methodology mentioned allows designing a ventilation system for the workshop of an engineering enterprise in accordance with specific conditions of its operation it also allows defining a reliable value of economy of funds taking into account actual loss.

Supercritical CO2 Binary Mixtures for Recompression Brayton s-CO2 Power Cycles Coupled to Solar Thermal Energy Plants

In this work, an evaluation and quantification of the impact of using mixtures based on Supercritical Carbon Dioxide "s-CO2" (s-CO2/COS, s-CO2/H2S, s-CO2/NH3, s-CO2/SO2) are made as a working fluid in simple and complex recompression Brayton s-CO2 power cycles configurations that have pressure drops in their components. These cycles are coupled to a solar thermal plant with parabolic-trough collector (PTC) technology. The methodology used in the calculation performance is to establish values of the heat recuperator total conductance (UAtotal) between 5 and 25 MW/K. The main conclusion of this work is that the cycle's efficiency has improved due to s-CO2 mixtures as working fluid; this is significant compared to that obtained using the standard fluid (pure s-CO2). Furthermore, a techno-economic analysis is carried out that compares each configuration's costs using pure s-CO2 and a mixture of s-CO2/COS with a molar fraction (70/30) respectively as working fluid where relevant results are obtained. These results show that the best configuration in terms of thermal efficiency and cost is the RCC-RH for pure sCO2 with values ​​of 41.25% and 2811 $/kWe, while for the mixture sCO2/COS, the RCC-2RH configuration with values ​​of 45, 05% and 2621 $/kWe is optimal. Using the mixture costs 6.75% less than if it is used the standard fluid (s-CO2).

OPTIMIZATION OF ENERGY EFFICIENCY OF A HEAT RECUPERATOR ON THE BASIS OF UNDERGROUND COAL GASIFICATION

Mining of the off-balanced and balanced reserves of mines, being under closure or completing their operation, required the implementation of mobile, complex, and environmentally friendly development technologies based on the processes of well underground coal gasification (WUCG) that unites mining of coal and its energy-chemical use. Environmental friendliness of the WUCG process is possible due to its controllability, hermeticity of the underground gas generator, and complex use of cogeneration technologies in the closed cycle of purification and processing of gasification products. The set engineering tasks were performed using analytical studies, bench studies and field studies. Efficiency of thermal energy generation were studies using rocks enclosing the underground gasifier and generator gases. These sources being the basic heat generating segments of energy chemical complex for coal gasification being formed at the territories of operating coal mines or mines at the stage of their closure. Prospects of coal gasification and thermal energy generation using rock disposals of coal mines have been estimated.

Design of a radiative heat recuperator for steel processes

In recent years, there has been an increasing interest in the recovery of the waste heat of steel and glass processes. This work proposes a numerical study of a waste heat exchanger system for steel production processes. The radiative energy is transferred to a commercial oil, which can be used to produce electricity. The behavior of the recuperator is analysed using a 3D numerical model, considering the constrains of a real production plant. The influence of the radiation properties of the materials on the temperature and heat transfer rate are also examined. The results show that the absorptivity of the tubes influences significantly the absorbed waste heat. Furthermore, heterogeneous mass flow distribution should be applied to optimize the total heat transfer rate.