The DLR High Temperature Heat Pump Pilot Plants

The new German Aerospace Center’s (DLR) Institute of Low-Carbon Industrial Processes is currently developing new prototypes of high temperature heat pumps (HTHP). Those are needed to process streams in industrially relevant high temperature ranges that cannot be achieved with state-of-the-art heat pumps. This novel technology will deliver process heat and, if required, additional cooling for industrial applications, which currently utilize fossil fuels. Furthermore, the valorization of industrial exhaust heat can result in considerable primary energy savings for the same amount of process heat delivered. The new DLR institute is based in two locations in Germany, Cottbus and Zittau. Currently, two heat pump concepts are being developed. The first one is a HTHP based on the Brayton cycle with air as the working fluid and will be placed in Cottbus (CoBra). The second one is based on the Rankine cycle using water as the working fluid and will be placed at the second location Zittau (ZiRa). The general technical scope for the heat pumps will be to achieve a heat delivery of at least 500 °C and at the same time demonstrate an industrial scale HTHP providing power in the MegaWatt-range. Along this way, smaller pilot plants were designed. These are currently under construction (Pilot CoBra) or in the detailed planning and procurement phase (Pilot ZiRa). The pilot plants of smaller size / performance and sink temperature (~200 – 300°C) will be on one hand side perfect as learning and innovation platforms but on the other side many industrial processes need heat in this temperature range and also in that size. At the moment, extensive research is taking place on developing and enhancing the performance of various components of the heat pump. For example, two compressor stages will be used in Pilot ZiRa to raise the pressure of steam to the required level without compromising the efficiency of the cycle. This is done by inter-stage cooling between the compressors in order to avoid very high temperature at the outlet and consequently increasing the density of steam. Another research project deals with an innovative concept of a supersonic two- phase steam ejector to be integrated in ZiRa. Research is taken place at the moment to investigate new ejector designs and to test it experimentally in our ZiRa pilot plant. On the other hand, the complete cycle is currently being optimized to reduce energy losses in cycle components

VpreB serves as an invariant surrogate antigen for selecting immunoglobulin antigen-binding sites

Developmental checkpoints eliminate B cells that synthesize defective immunoglobulin (Ig) heavy (HC) and light (LC) chains. The first checkpoint tests mHCs paired with VpreB/l5 in a pre-B cell receptor (pre-BCR) to determine whether the mHC will be able to bind conventional LCs to form membrane IgM. VpreB and l5 also create a sensing site that interacts with the mHC antigen-binding region complementarity-determining region (CDR)\u2013H3; however, whether this site contributes to Ig repertoire selection and function is unknown. We analyzed the amino acid content of CDR-H3s from HCs cloned from living and apoptotic pre-B cells and from IgG-antigen structures. Using a panel of DH gene\u2013targeted mice, we showed that progressively reducing CDR-H3 tyrosine content increasingly impaired pre-BCR checkpoint passage. Counting from cysteine at framework 3 position 96, we found that VpreB particularly selected for tyrosine at CDR-H3 position 101 and that Y101 also bound antigen in IgG-antigen structures. Therefore, in addition to its stabilization role in the pre-BCR, VpreB also acts as an early invariant antigen by selecting for particular CDR-H3 amino acids. These interactions shape the specificity of the IgG humoral response and may thus impose limitations on development of certain neutralizing antibodies

HIGH TEMPERATURE HEAT PUMP CASCADE SYSTEMS WITH WATER (R718) AS REFRIGERANT

The heat demand of industrial processes is still mostly covered by fossil fuels, especially at temperatures above 160°C. The installation of high temperature heat pumps (HTHP) that can operate at these temperatures is an effective way to reduce industrial CO2-emissions and primary energy consumption. Water can be an attractive refrigerant due to its high critical point and environmental sustainability. However, using water as refrigerant also requires a waste heat source of high temperature, since any heat source below 100°C would result in sub-atmospheric evaporation, leading to more expensive equipment. If low temperature heat sources or even ambient heat should be utilized, the HTHP would consist of two coupled heat pumps, a cascade system. In this theoretical study a cascade high temperature heat pump process is presented and simulated operating with water and R1336mzz(Z)e. The heat pump consists of multiple compression stages with intercooling in order to increase the COP. Heat sink temperatures of up to 250°C were investigated and an optimal process design was identified for several heat sink and -source temperatures. The calculated COPs ranged from 1.5 under challenging conditions to up to 2.2 at moderate temperature lifts. The crucial evaporation pressure of the water heat pump has been close to one bar for most of the studies, so the installation of vacuum equipment could be avoided

Modelling of Two-Phase Water Ejector in Rankine Cycle High Temperature Heat Pumps

Industrial high temperature heat pumps (HTHPs) can provide carbon-free process heat when operated with renewable energy sources. Using water as the working medium greatly increases the possible range of operation without the detrimental effects of traditional working fluids. One main challenge with this type of heat pump is the high compression ratio required to achieve a given temperature lift. As a result, water based heat pumps need several compression stages. Furthermore, the steam leaving the compressor is highly superheated. Ejectors driven by high pressure condensate allow to de-superheat the steam from the compressor outlet while simultaneously increasing its pressure. Thereby, the required power for compression as well as the number of compression stages can be reduced. This paper studies how the implementation of the two-phase water ejector influences the thermodynamic performance of Rankine cycle HTHP using a thermodynamic model of the ejector. Several cycle architectures are developed to study the ejector integration in the heat pump cycle, including traditional single-stage and multi-stage cycles. The cycles studies are conducted in the Modelica language, in the Modelon Impact environment. The study aims at informing about new developments in two-phase water ejectors and their application potential in Rankine cycle HTHPs. First simulations suggest an efficiency improvement of about 10% through the use of an ejector in the heat pump cycle

Entwicklung eines Wasserdampfverdichters

Die Bereitstellung von Prozesswärme erfolgt in vielen Industriebetrieben durch Dampf, der durch die Verbren-nung fossiler Energieträger erzeugt wird. Bis spätestens 2050 müssen diese durch regenerative Energiequellen ersetzt werden. Dabei bietet sich insbesondere bei Dampfnetzen die Nutzung von Ab- und Umweltwärme, z.B. Solar- oder Geothermie, in Kombination mit einer Dampfverdichtung an. Industriell und prototypisch verfügbar sind verschiedene Verdichtertypen, die allerdings zumeist nur geringe Druckverhältnisse und damit Temperaturhübe erlauben und aus wirtschaftlichen Gründen meist nur für große Leistungen angeboten werden. Insbesondere bei kleineren Betrieben mit nur einer Druckstufe des Dampfnetzes ergeben sich Anwendungspo-tentiale für die Dampfverdichtung unter der Voraussetzung, dass entsprechende Kompressoren zur Verfügung stehen. Am Institut für CO2-arme Industrieprozesse wird derzeit eine geschlossene Wärmepumpe mit Dampf als Arbeits-mittel aufgebaut. Für diese wird ein Radialverdichter mit hohem Druckverhältnis bei kleinen Volumenströmen entwickelt, der in einer weiteren Entwicklungsstufe bei verschiedenen Anwendungen zum Einsatz kommen kann. Zum Erreichen der Prozessparameter werden sehr hohe Umfangsgeschwindigkeiten benötigt, die sowohl eine strukturmechanische als auch aerodynamische Optimierung des Impellers erforderlich machen. In diesem Vortrag werden die auf dem Markt verfügbaren Verdichtersysteme, mögliche Anwendungsfälle und die Entwicklung des Turboverdichters vorgestellt

The Role of the Pre-B Cell Receptor in B Cell Development, Repertoire Selection, and Tolerance

Around four decades ago, it had been observed that there were cell lines as well as cells in the fetal liver that expressed antibody μ heavy (μH) chains in the apparent absence of bona fide light chains. It was thus possible that these cells expressed another molecule(s), that assembled with μH chains. The ensuing studies led to the discovery of the pre-B cell receptor (pre-BCR), which is assembled from Ig μH and surrogate light (SL) chains, together with the signaling molecules Igα and β. It is expressed on a fraction of pro-B (pre-BI) cells and most large pre-B(II) cells, and has been implicated in IgH chain allelic exclusion and down-regulation of the recombination machinery, assessment of the expressed μH chains and shaping the IgH repertoire, transition from the pro-B to pre-B stage, pre-B cell expansion, and cessation

Atomic topological groups

We investigate the atoms of the lattice L(G) of all group topologies on a group G by using the close connection between atoms of L(G), and minimal Hausdorff elements of the lattice L (G/N) for appropriate quotient groups G/N. We show, among others, that virtually hypercentral groups have only degenerate atoms

In the Absence of Central pre-B Cell Receptor Selection, Peripheral Selection Attempts to Optimize the Antibody Repertoire by Enriching for CDR-H3 Y101

Sequential developmental checkpoints are used to “optimize” the B cell antigen receptor repertoire by minimizing production of autoreactive or useless immunoglobulins and enriching for potentially protective antibodies. The first and apparently most impactful checkpoint requires μHC to form a functional pre-B cell receptor (preBCR) by associating with surrogate light chain, which is composed of VpreB and λ5. Absence of any of the preBCR components causes a block in B cell development that is characterized by severe immature B cell lymphopenia. Previously, we showed that preBCR controls the amino acid content of the third complementary determining region of the H chain (CDR-H3) by using a VpreB amino acid motif (RDR) to select for tyrosine at CDR-H3 position 101 (Y101). In antibodies bound to antigen, Y101 is commonly in direct contact with the antigen, thus preBCR selection impacts the antigen binding characteristics of the repertoire. In this work, we sought to determine the forces that shape the peripheral B cell repertoire when it is denied preBCR selection. Using bromodeoxyuridine incorporation and evaluation of apoptosis, we found that in the absence of preBCR there is increased turnover of B cells due to increased apoptosis. CDR-H3 sequencing revealed that this is accompanied by adjustments to DH identity, DH reading frame, JH, and CDR-H3 amino acid content. These adjustments in the periphery led to wild-type levels of CDR-H3 Y101 content among transitional (T1), mature recirculating, and marginal zone B cells. However, peripheral selection proved incomplete, with failure to restore Y101 levels in follicular B cells and increased production of dsDNA-binding IgM antibodies