AutoML-based predictive framework for predictive analysis in adsorption cooling and desalination systems

Adsorption cooling and desalination systems have a distinct advantage over other systems that use low-grade waste heat near ambient temperature. Since improving their performance, including reliability and failure prediction, is challenging, developing an efficient diagnostic system is of great practical significance. The paper introduces artificial intelligence (AI) and an automated machine learning approach (AutoML) in a real-life application for a computational diagnostic system of existing adsorption cooling and desalination facilities. A total of 1769 simulated data points containing data indicating a failure status are applied to develop a comprehensive AI-based Diagnostic (AID) system covering a wide range of 42 input parameters. The paper introduces a conditional monitoring system for adsorption cooling and desalination systems. The novelty of the presented study mainly consists of two aspects. First, the intelligent system predicts the health or failure states of various components in a complex three-bed adsorption chiller installation using the extensive input data sets of 42 different operating parameters. The developed AID expert tool, based on selecting the best from 42 models generated by the DataRobot platform, was validated on the complex, existing three-bed adsorption chiller. The AID system correctly identified healthy and failure states in various installation components. The developed expert system is very efficient (AUC = 0.988, RMSE = 0.20, LogLoss = 0.14) in predicting emergency states. The proposed method constitutes a quick and easy technique for failure prediction and represents a complementary tool compared to the other condition monitoring methods

Modelling of SO2 and NOx Emissions from Coal and Biomass Combustion in Air-Firing, Oxyfuel, iG-CLC, and CLOU Conditions by Fuzzy Logic Approach

Chemical looping combustion (CLC) is one of the most advanced technologies allowing for the reduction in CO2 emissions during the combustion of solid fuels. The modified method combines chemical looping with oxygen uncoupling (CLOU) and in situ gasification chemical looping combustion (iG-CLC). As a result, an innovative hybrid chemical looping combustion came into existence, making the above two technologies complementary. Since the complexity of the CLC is still not sufficiently recognized, the study of this process is of a practical significance. The paper describes the experiences in the modelling of complex geometry CLC equipment. The experimental facility consists of two reactors: an air reactor and a fuel reactor. The paper introduces the fuzzy logic (FL) method as an artificial intelligence (AI) approach for the prediction of SO2 and NOx (i.e., NO + NO2) emissions from coal and biomass combustion carried out in air-firing; oxyfuel; iG-CLC; and CLOU conditions. The developed model has been successfully validated on a 5 kWth research unit called the dual fluidized bed chemical looping combustion of solid fuels (DFB-CLC-SF)

Optimisation of Operation of Adsorption Chiller with Desalination Function

The demand for electricity is growing rapidly along with economic development and increasing population. At present, its production is mainly based on non-renewable sources, which has negative impacts on the environment and contributes to global warming. A large proportion of the produced electricity is consumed by refrigeration equipment. Climate change and the progress of civilisation are additionally increasing the demand for cooling, with increasing electricity consumption as a consequence. One of the options for obtaining eco-friendly cooling is the use of adsorption chillers. These devices are powered by low-temperature heat and their operation only requires a small amount of electrical energy. The source of low-temperature heat can be, e.g., waste heat generated in many industrial processes. Its use allows one to increase energy efficiency and achieve additional financial benefits. However, adsorption chillers are characterised by low coefficients of performance. This paper presents possibilities to improve their performance. It also presents the results of tests carried out on a three-bed adsorption chiller with desalination function. The aim of the investigation was to determine the effect of the cycle time on the coefficient of performance (COP) and specific cooling power (SCP). The working pair was silica gel and water. The results confirmed the effect of the duration of adsorption and desorption on the COP and SCP of the adsorption chiller. Increasing the duration of the cycle led to an increase in the COP

Effect of Additives on the Sorption Kinetics of a Silica Gel Bed in Adsorption Chiller

The article presents experimental results of the metal-based and carbon nanotube additives influence on sorption kinetics of a silica-gel-based adsorption bed in an adsorption chiller. The purpose of the doping is to improve the efficiency of sorption processes within the bed by use of metallic and non-metallic additives characterized by higher thermal diffusivity than basic adsorption material. The higher the thermal conductivity of the bed, the faster the sorption processes take place, which directly translates into greater efficiency of the refrigerator. In this study, sorption kinetics of pure silica gel sorbent doped with a given amount of aluminum (Al) and copper (Cu) powders and carbon nanotubes (CNT) were analyzed. The tests were performed on DVS Dynamic Gravimetric Vapor Sorption System apparatus used for dynamic vapor sorption measurements. A decrease in the amount of adsorbed water was observed with an increase in the mass share of the additives in the performed studies. Experimental results show that, CNTs seems to be the most promising additive as the sorption process time was reduced with the smallest decrease in water uptake. Any significant reduction of adsorption time was noted in case of the Al addition. Whereas, in case of Cu doping, delamination of the mixture was observed

The Effects of Using Steam to Preheat the Beds of an Adsorption Chiller with Desalination Function

Adsorption chillers are a promising alternative to traditional compressor-based devices. Adsorption chillers can be supplied with low- or medium-temperature waste heat or heat from renewable energy sources. In addition, they can be used for water desalination purposes. Thus, the adsorption chillers are unique devices that meet essential problems of the modern world: a need to limit the negative impact of humankind on the natural environment and growing problems with access to drinking water. However, adsorption chillers also have disadvantages, including ineffective operation and large size. Therefore, in this paper, the influence of steam utilization on the operation of an adsorption chiller with water desalination function was investigated experimentally, which has not been done before. The research was carried out on the adsorption chiller, working on a silica gel–water pair, installed in the AGH UST Center of Energy. The chiller was modified to preheat the sorbent with the use of steam. The results show that the use of steam instead of water for preheating the bed leads to higher temperatures in the heat exchanger and the bed. As a result, heat transfer from the heating medium to the bed is more intense, and a significant shortening of the desorption process is observed. In the case of using steam for preheating, the desorption time was about 30 s, while for water, it was 300 s. Thanks to this solution, it is possible to reduce the size of the device and increase its efficiency. The proposed solution opens a new course of research on adsorption chillers and broadens the horizon of their applications, as steam is a by-product of many industrial processes

An influence of low-stability region on dense gas phenomena and their peculiarities in the ORC fluids

An existence of low stability region in the dense vapours and its influence on some peculiarities in behaviour of selected dry and isentropic ORC fluids is discussed. The retrograde phenomena in the flow of BZT fluids [1.] can be simply related to the mechanical and thermodynamic stability parameters. These new refrigerant and their properties have been analysed based on the software tools REFPROP v.9.1 [2.]. Test examples have confirmed an importance of low thermodynamic stability area in the vicinity of saturation boundary line and neighbourhood of critical point of the fluid. The analytical results have been obtained for selected pure fluids applicable in the ORC and heat pump technology such C4H10, C6H5CH3, C12H26, R123, R134a, R227ea, R245fa, low GWP hydrofluoroolefins (R1234xxX)and a group of linear and cyclic siloxanes

An influence of low-stability region on dense gas phenomena and their peculiarities in the ORC fluids

An existence of low stability region in the dense vapours and its influence on some peculiarities in behaviour of selected dry and isentropic ORC fluids is discussed. The retrograde phenomena in the flow of BZT fluids [1.] can be simply related to the mechanical and thermodynamic stability parameters. These new refrigerant and their properties have been analysed based on the software tools REFPROP v.9.1 [2.]. Test examples have confirmed an importance of low thermodynamic stability area in the vicinity of saturation boundary line and neighbourhood of critical point of the fluid. The analytical results have been obtained for selected pure fluids applicable in the ORC and heat pump technology such C4H10, C6H5CH3, C12H26, R123, R134a, R227ea, R245fa, low GWP hydrofluoroolefins (R1234xxX)and a group of linear and cyclic siloxanes

The Impact of Additives on the Main Properties of Phase Change Materials

The main drawback of phase change materials (PCMs) is their low thermal conductivity, which limits the possibilities of a wide range of implementations. Therefore, the researchers, as found in the literature, proposed several methods to improve the thermal conductivity of PCMs, including inserting high thermal conductivity materials in nano-, micro-, and macro-scales, as well as encapsulation of PCMs. However, these inserts impact the other properties of PCMs like latent heat, melting temperature, thermal stability, and cycling stability. Hence, this paper aims to review the available in the open literature research on the main properties of enhanced PCMs that undergo solid–liquid transition. It is found that inserting high thermal conductivity materials and encapsulation results in improved thermal conductivity of PCMs, but it decreases their latent heat. Moreover, the insertions can act as nucleating agents, and the supercooling degree can be reduced. Some of the thermal conductivity enhancers (TCEs) may prevent PCMs from leakage. However, some test results are inconsistent and some seem to be questionable. Therefore, this review indicates these discrepancies and gaps in knowledge and points out possible directions for further research

The thermoelectric generators use for waste heat utilization from conventional power plant

On the base of available data, it is estimated that the industrial approx. 20-50% of the energy is removed into the atmosphere as waste heat include in the form of hot flue gases, cooling water, the heat losses from the equipment hot surfaces or heated products. However, according to the data from the US market in 2010, in the form of waste heat is emitted more than 96 · 106 TJ annually (2.7 · 1010 MWh), means more than 57% of the produced energy. According to statistics, currently the energy production in the US amounts to approx. 26% of the world's energy production. Assuming the same indicators, the total annual amount of waste heat in the scale of the world equals 370 · 106 TJ (10.4 · 1010 MWh). One of the ways to increase the energy efficiency of manufacturing processes and reducing energy consumption and negative impacts to the environment is the use of waste energy [1,2,3] In this work it was investigated the possibilities of the waste heat utilization from conventional thermal power plant using thermoelectric generators, the operation of which is based on the Seebeck effect

The thermoelectric generators use for waste heat utilization from conventional power plant

On the base of available data, it is estimated that the industrial approx. 20-50% of the energy is removed into the atmosphere as waste heat include in the form of hot flue gases, cooling water, the heat losses from the equipment hot surfaces or heated products. However, according to the data from the US market in 2010, in the form of waste heat is emitted more than 96 · 106 TJ annually (2.7 · 1010 MWh), means more than 57% of the produced energy. According to statistics, currently the energy production in the US amounts to approx. 26% of the world's energy production. Assuming the same indicators, the total annual amount of waste heat in the scale of the world equals 370 · 106 TJ (10.4 · 1010 MWh). One of the ways to increase the energy efficiency of manufacturing processes and reducing energy consumption and negative impacts to the environment is the use of waste energy [1,2,3] In this work it was investigated the possibilities of the waste heat utilization from conventional thermal power plant using thermoelectric generators, the operation of which is based on the Seebeck effect