Assessment of Energy Efficiency and Flexibility Measures in Electrified Process Heat Generation Based on Simulations in the Animal Feed Industry

A large part of the energy demand in industry can be attributed to the provision of heat. To reduce greenhouse gas emissions, the energy demand must be reduced and renewable energies must be integrated. Since the capacity of renewable heat sources is often limited, the electrification of processes is a promising solution. Due to the increasing share of fluctuating renewable energies in the electricity mix, it is advantageous if consumption can be flexibly controlled. Thus, in-house energy management in industry faces many challenges. On the one hand, general consumption must be reduced through the efficient use of energy; on the other hand, load shifting and flexible use of energy may reduce both, emissions and costs. Often, however, both alternatives interfere with each other, and an either-or decision is the result. A practical efficiency and electrification measure is the use of heat pumps. This can reduce the final energy demand for heat generation, but the constant mode of operation due to the coupling of heat sources and heat sinks leaves little room for grid-serving operation. Other electrification options, such as an electric boiler, offer greater flexibility in combination with thermal storage, but have lower efficiency. To quantify the energy requirements as a basis for comparison, the heat pump as an energy efficiency option and an electrode boiler in combination with a thermal storage tank as a flexibility option are simulated along a typical demand profile in the animal feed industry. To ensure maximum heat recovery, the heat pump is optimised using pinch analysis and designed for the respective process. For the flexibility option, an operational optimisation is carried out using Linear Programming. In addition, a hybrid variant is considered using Mixed Integer Linear Programming. While no electrification measure is currently more economical than the gas reference case, the electric boiler option is significantly more expensive than a Very-High-Temperature Heat Pump. The hybrid can reduce the size of the heat pump and get a further benefit from flexible prices, which gives it cost advantages

Ecological and Economic Feasibility of Inductive Heating for Sustainable Press Hardening Processes

Press hardening is an established process for the production of high-strength lightweight structural automotive parts, like the B-pillar. While lightweight design is an important aspect of emission reduction during the use phase, emissions arising in other phases of the automotive lifecycle also need to be considered. Roller-hearth-furnaces, as used during the press hardening process, present a non-negligible source of greenhouse gas emissions in part production processes. Alternative heating methods, such as inductive heating, may pose a possibility to reduce emissions during the manufacturing process, while also offering additional advantages in high process flexibility, high energy efficiency and low space requirements. However, there are multiple challenges when it comes to inductive heating of sheet metal for industrial processes, such as homogeneity of heating and resulting material properties. Therefore, various investigation on the usability of inductive heating for press hardening process have been conducted. Recently, an inductive heating process utilizing a longitudinal field inductor for industrial press hardening has been developed, showing good results in regard to process homogeneity, heating times and material properties. This process is used as a baseline for an ecological and economical assessment of inductive heating for industrial press hardening processes in comparison to traditional gas-fired furnaces. The reference values for a comparison on cost and emission are based on a gas-fired conveyor furnace with constant speed used for the heating of sheet metal for press hardening. The share of furnace operation modes, like standby and production with varying good-mass flows, as well as resulting natural gas demands are provided. From this data, specific energy requirements of heated sheet metal can be derived for various material mass flows and utilization scenarios, which serve as a baseline for the cost and emission comparison.  The objective of this study is to determine the emissions and costs for inductive heating compared to conventional gas-fired roller-hearth furnaces for different parameter-set of boundary conditions like product mass flow, energy prices, emission factors depending on energy transition scenarios. Based on this evaluation matrix, break-even conditions favoring inductive heating can be identified.&nbs

Detection of 133^{133}Xe from the Fukushima nuclear power plant in the upper troposphere above Germany

After the accident in the Japanese Fukushima Dai-ichi nuclear power plant in March 2011 large amounts of radioactivity were released and distributed in the atmosphere. Among them were also radioactive noble gas isotopes which can be used as tracers to test global atmospheric circulation models. This work presents unique measurements of the radionuclide $^{133}$Xe from Fukushima in the upper troposphere above Germany. The measurements involve air sampling in a research jet aircraft followed by chromatographic xenon extraction and ultra-low background gas counting with miniaturized proportional counters. With this technique a detection limit of the order of 100 $^{133}$Xe atoms in litre-scale air samples (corresponding to about 100 mBq/m$^3$) is achievable. Our results provide proof that the $^{133}$Xe-rich ground level air layer from Fukushima was lifted up to the tropopause and distributed hemispherically. Moreover, comparisons with ground level air measurements indicate that the arrival of the radioactive plume at high altitude over Germany occurred several days before the ground level plume.Comment: 8 pages, 5 figure

Hardware in the loop evaluation of a hybrid heating system for increased energy efficiency and management

This study presents the tests of a hybrid heating prototype, designed for retrofitting thermal treatment plants like pasteurization, to use hot water and steam in controlled ratios. In the food industry, steam with a temperature above 140°C usually supplies the thermal production processes. The majority of processes require temperatures below 100°C and could be supplied more eficiently by cogeneration, heat recovery or heat pumps. These low temperature heat sources can only be combined with the rigid steam system if the demand structure is changed to a hybrid use of hot water below 100°C and steam. The hybrid heating system (H2S) increases the energy efficiency by integrating the highest possible amount of low temperature heat and responds to sudden changes in the supply structure, like demand response strategies on intermittent renewable energies and the changing availability of hot water and steam. The technical implementation is realised by a hydraulic interconnection of heat exchangers and valves. A smart algorithm controls the integration of hot water and steam into the thermal process. For reasons of food safety and product quality defined process temperatures have to be met. Prerequisite for functional verification on a laboratory scale is a simulation of the process heat demand and potential of hot water during the entire production cycle. The load profiles and relevant process parameters are passed in real time to a hardware-in-the loop (HIL) test-bed and returned to the simulation respectively. Two scenarios, hot water integration from heat pump and demand response management with a gas engine CHP and an electrical steam generator, were evaluated and the functionality of the H2S was proved. Up to 78 % of the final energy demand can be reduced by the H2S based implementation of a heat pump. The control response of the system, even with fluctuating hot water potential and temperature, met the requirements of the dairy industry

Design of robust total site heat recovery loops via Monte Carlo simulation

For increased total site heat integration, the optimal sizing and robust operation of a heat recovery loop (HRL) are prerequisites for economic efficiency. However, sizing based on one representative time series, not considering the variability of process streams due to their discontinuous operation, often leads to oversizing. The sensitive evaluation of the performance of an HRL by Monte Carlo (MC) simulation requires sufficient historical data and performance models. Stochastic time series are generated by distribution functions of measured data. With these inputs, one can then model and reliably assess the benefits of installing a new HRL. A key element of the HRL is a stratified heat storage tank. Validation tests of a stratified tank (ST) showed sufficient accuracy with acceptable simulation time for the variable layer height (VLH) multi-node (MN) modelling approach. The results of the MC simulation of the HRL system show only minor yield losses in terms of heat recovery rate (HRR) for smaller tanks. In this way, costs due to oversizing equipment can be reduced by better understanding the energy-capital trade-off

Isoforms of Retinol binding protein 4 (RBP4) are increased in chronic diseases of the kidney but not of the liver

<p>Abstract</p> <p>Background</p> <p>The levels of retinol-binding protein 4 (RBP4) – the carrier protein for Vitamin A in plasma – are tightly regulated under healthy circumstances. The kidney, the main site of RBP4 catabolism, contributes to an elevation of RBP4 levels during chronic kidney disease (CKD) whereas during chronic liver disease (CLD) RBP4 levels decrease. Little is known about RBP4 isoforms including apo-RBP4, holo-RBP4 as well as RBP4 truncated at the C-terminus (RBP4-L and RBP4-LL) except that RBP4 isoforms have been reported to be increased in hemodialysis patients. Since it is not known whether CLD influence RBP4 isoforms, we investigated RBP4 levels, apo- and holo-RBP4 as well as RBP4-L and RBP4-LL in plasma of 36 patients suffering from CKD, in 55 CLD patients and in 50 control subjects. RBP4 was determined by ELISA and apo- and holo-RBP4 by native polyacrylamide gel electrophoresis (PAGE). RBP4-L and RBP4-LL were analyzed after immunoprecipitation by mass spectrometry (MALDI-TOF-MS).</p> <p>Results</p> <p>RBP4 isoforms and levels were highly increased in CKD patients compared to controls (P < 0.05) whereas in CLD patients RBP4 isoforms were not different from controls. In addition, in hepatic dysfunction RBP4 levels were decreased whereas the amount of isoforms was not affected.</p> <p>Conclusion</p> <p>The occurrence of RBP4 isoforms is not influenced by liver function but seems to be strongly related to kidney function and may therefore be important in investigating kidney function and related disorders.</p

The control of hydrogen sulfide on benthic iron and cadmium fluxes in the oxygen minimum zone off Peru

Sediments in oxygen-depleted marine environments can be an important sink or source of bio-essential trace metals in the ocean. However, the key mechanisms controlling the release from or burial of trace metals in sediments are not exactly understood. Here, we investigate the benthic biogeochemical cycling of Fe and Cd in the oxygen minimum zone off Peru. We combine bottom water profiles, pore water profiles, as well as benthic fluxes determined from pore water profiles and in-situ from benthic chamber incubations along a depth transect at 12° S. In agreement with previous studies, both concentration-depth profiles and in-situ benthic fluxes indicate a Fe release from sediments into bottom waters. Diffusive Fe fluxes and Fe fluxes from benthic chamber incubations are roughly consistent (0.3–17.1 mmol m−2 y−1), indicating that diffusion is the main transport mechanism of dissolved Fe across the sediment-water interface. The occurrence of mats of sulfur oxidizing bacteria on the seafloor represents an important control on the spatial distribution of Fe fluxes by regulating hydrogen sulfide (H2S) concentrations and, potentially, Fe sulfide precipitation within the surface sediment. Removal of dissolved Fe after its release to anoxic bottom waters is rapid in the first 4 m away from the seafloor (half-life  25, indicating that downward diffusion of Cd across the sediment-water interface is of subordinate importance for Cd removal from benthic chambers. As Cd removal in benthic chambers co-varies with H2S concentrations in the pore water of surface sediments, we argue that Cd removal is mediated by precipitation of CdS within the chamber. A mass balance approach, taking into account the contributions of diffusive fluxes and fluxes measured in benthic chambers as well as Cd delivery with organic material suggests that CdS precipitation in the near-bottom water could make an important contribution to the overall Cd mass accumulation in the sediment solid phase. According to our results, the solubility of trace metal sulfide minerals (Cd << Fe) is a key-factor controlling trace metal removal and consequently the magnitude as well as the temporal and spatial heterogeneity of sedimentary fluxes. We argue that depending on their sulfide solubility, sedimentary source or sink fluxes of trace metals will change differentially as a result of declining oxygen concentrations and an associated expansion of sulfidic surface sediments. Such a trend could cause a change in the trace metal stoichiometry of upwelling water masses with potential consequences for marine ecosystems in the surface ocean

Heat pump bridge analysis using the modified energy transfer diagram

Heat pumps are the key technology to decarbonise thermal processes by upgrading industrial surplus heat using renewable electricity. Existing insight-based integration methods refer to the idealised Grand Composite Curve requiring the full exploitation of heat recovery potential but leave the question of how to deal with technical or economic limitations unanswered. In this work, a novel Heat Pump Bridge Analysis (HPBA) is introduced for practically targeting technical and economic heat pump potential by applying Coefficient of Performance curves into the Modified Energy Transfer Diagram (METD). Removing cross-Pinch violations and operating heat exchangers at minimum approach temperatures by combined application of Bridge Analysis increases the heat recovery rate and reduce the temperature lift to be pumped at the same time. The insight-based METD allows the individual matching of heat surpluses and deficits of individual streams with the capabilities and performance of different market-available heat pump concepts. For an illustrative example, the presented modifications based on HPBA increase the economically viable share of the technical heat pump potential from 61% to 79%