Jako Veldhuis | ECN Energy Research Centre of the Netherlands (original) (raw)
Papers by Jako Veldhuis
Thermochimica Acta, 2002
Structural, thermodynamic and phase properties in the Na2S–H2O system for application in a chemic... more Structural, thermodynamic and phase properties in the Na2S–H2O system for application in a chemical heat pump have been investigated using XRD, TG/DTA and melting point and vapour pressure determinations. Apart from the known crystalline phases Na2S·9H2O, Na2S·5H2O and Na2S a new phase Na2S·2H2O has been proven to exist. Na2S·12H2O is not a phase but a 3:1 mixture of Na2S and
Heat-driven heat pumps based on the principle of chemisorption have been researched worldwide. Su... more Heat-driven heat pumps based on the principle of chemisorption have been researched worldwide. Such research typically focuses either on fundamental materials properties such as sorption isotherms, thermal conductivity and heat of sorption, or on the development and performance of complete systems. Also at ECN the research shows this typical pattern with publications on the fundamental thermodynamic properties on ammonia reactions of lithium chloride and magnesium chloride together with results on complete systems . However, when trying to connect the material properties to the system's performance, for example by using model calculations, various uncertainties on heat exchanger/sorption reactor level remain. These uncertainties, such as reaction kinetics, heat and mass transfer limitations for given specific geometries and conditions but also effects due to repeated sorption, pose a considerable problem for further development, improvement and scaling up of the system. In order to get a better understanding of the performance of the sorption reactor/heat exchanger design and sorbent bed loading, an experimental setup has been developed. This setup allows measuring the performance of various ammonia-sorbent reactions with various sorption reactor/heat exchanger designs under well-controlled and well-monitored process conditions similar to the heat pump conditions. This setup measures the ammonia uptake and release under well-controlled conditions with temperatures that can be varied from ambient temperature up to 200 o C and ammonia pressures that can be varied between 0.02 to 2 MPa. These conditions can be set independently and repeated at regular time-intervals. Besides mass-flow meters, pressure and temperature sensors, the setup also contains an endoscope to observe the macroscopic structural changes in the material during uptake and release of ammonia. After initial testing, the setup is now ready for the first experiments on different heat exchanger designs and sorbent materials. The paper includes a description of the setup and the first experimental results. P reaction -oil average [W] P netto oil [W] Energy balans [kJ] Time [h:mm:ss] Power [W] Energy balans [kJ]
ChemInform
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Proceedings of the International Symposium on Innovative Materials for Processes in Energy Systems 2010, 2010
Heat pumps type II can be used for upgrading industrial waste heat to above pinch temperatures, w... more Heat pumps type II can be used for upgrading industrial waste heat to above pinch temperatures, with a typical lift from 130 o C to 180 o C. At ECN such a heat pump is developed based on the reaction of ammonia with lithium chloride and magnesium chloride as respectively the low and high temperature salt. The thermodynamic properties of these salts are required to determine temperature lift and coefficient of performance. This paper presents the behavior of the low temperature salt, lithium chloride, under typical working conditions with temperatures ranging from ambient to 150°C and ammonia pressures ranging from 0.3 to 30 bars. Measurements using an HPDSC, an autoclave and a custom-made ammonia pressure cell have been conducted to determine the pressure-temperature lines and their corresponding enthalpy and entropy values for lithium chloride ammonia complexes. The results show a direct transformation of lithium chloride mono-ammonia to lithium chloride tri-ammonia complex for ammonia pressures up to 4 bars and temperatures up to 90°C. At higher temperatures and pressures a stable, intermediate ammonia complex, lithium chloride di-ammonia complex, is formed. Under these conditions also a liquid phase has been observed. The latter can greatly affect the heat pump performance, both positive (no lattice degradation) as negative (escape from matrix, form impenetrable film).
Ninth International IBPSA Conference, …, 2005
In a survey recently conducted by ECN and the University of Utrecht in The Netherlands [Visscher,... more In a survey recently conducted by ECN and the University of Utrecht in The Netherlands [Visscher, Oonk et al, 2004]), several potential thermo chemical materials (TCM's) for seasonal storage of solar heat were determined. This first selection was performed on literature data and a set of selection criteria alone. A further selection was performed by a simulationand-comparison procedure between storage materials in a building simulation environment, with a hot water store as a reference case. In this way a few TCM's were identified that may offer chances for development of a new autonomous energy storage system with an effective energy storage density that is at least one order of magnitude larger than that of a hot water store.
Thermochimica Acta, 2002
Structural, thermodynamic and phase properties in the Na 2 S-H 2 O system for application in a ch... more Structural, thermodynamic and phase properties in the Na 2 S-H 2 O system for application in a chemical heat pump have been investigated using XRD, TG/DTA and melting point and vapour pressure determinations. Apart from the known crystalline phases Na 2 SÁ9H 2 O, Na 2 SÁ5H 2 O and Na 2 S a new phase Na 2 SÁ2H 2 O has been proven to exist. Na 2 SÁ 1 2 H 2 O is not a phase but a 3:1 mixture of Na 2 S and Na 2 SÁ2H 2 O, presumably stabilised by very slow dehydration kinetics. The vapour pressure-temperature equilibria of the sodium sulphide hydrates have been determined and a consistent set of thermodynamic functions for these compounds has been derived. XRD measurements indicate the topotactic character of the transitions between the hydration states. #
Journal of Power Sources, 1992
ABSTRACT At the Netherlands Energy Research Foundation, ECN, two approaches to the molten-carbona... more ABSTRACT At the Netherlands Energy Research Foundation, ECN, two approaches to the molten-carbonate fuel cell (MCFC) cathode lifetime problem have been investigated. In the first approach, efforts have been made to reduce the dissolution rate of the state-of-the-art NiO material by means of electrolyte additives. Thus far, it has been possible to obtain a reduction of c. 50% using alkaline-earth oxides or carbonates. The second approach is the development of alternative materials with good performance and very low dissolution rate, suitable to replace NiO. In this respect LiCoO2 is a promising candidate. In addition to a good in-cell behaviour, this material has a dissolution rate which is almost an order of magnitude lower than that of NiO, and its solubility shows favourable gas pressure dependences. In order to explain the significant differences in NiO, LiCoO2 and LiFeO2 performance, porous electrode modelling has been started. Preliminary results indicate that intrinsic materials properties, i.e., catalytic activity and electrical conductivity, play a crucial role in the observed polarization behaviour.
Journal of Power Sources, 2000
The polymer electrolytes are promising materials for the ever-growing need for high energy densit... more The polymer electrolytes are promising materials for the ever-growing need for high energy density power sources for power and traction applications. With an emphasis on lithium batteries, the field of polymer electrolytes has gone through a sort of three stages; dry solid systems, polymer gels, and polymer composites. The 'polymer gels' and the 'polymer composites', the former incorporating organic solvents, have shown room temperature conductivities as high as 10 y3 S cm y1 .The 'dry solid systems' presently suffer from poor ionic Ž y5 y1 . conductivities ; 10 S cm at 208C , but are safer than the former due to absence of any organic solvent which can cause environmental hazards. In the area of electrode systems, one can notice quite good performances by the organo-sulfur polymers as Ž .
Journal of Physics: Conference Series, 2012
ABSTRACT The characterization of the structural, compositional and thermodynamic properties of Mg... more ABSTRACT The characterization of the structural, compositional and thermodynamic properties of MgSO4.7H2O and MgCl2.6H2O has been done using in-situ X-ray Diffraction and thermal analyses (TG/DSC) under practical conditions for seasonal heat storage (Tmax=150°C, p(H2O)=13 mbar). This study showed that these two materials release heat after a dehydration/hydration cycle with energy densities of 0.38 GJ/m3 for MgSO4.7H2O and 0.71 GJ/m3 MgCl2.6H2O. The low heat release found for MgSO4.7H2O is mainly attributed to the amorphization of the material during the dehydration performed at 13 mbar which reduces its sorption capacity during the rehydration. MgCl2.6H2O presents a high energy density which makes this material interesting for seasonal heat storage in domestic applications. This material would be able to fulfil the winter heat demand of a passive house estimated at 6 GJ with a packed bed reactor of 8.5 m3. However, a seasonal heat storage system built with this material should be carefully set with a restricted temperature at 40°C for the hydration reaction to avoid the liquefaction of the material at lower temperature which limits its performances for long term storage.
Journal of The Electrochemical Society, 2002
Journal of The Electrochemical Society, 1992
European Polymer Journal, 1988
Abstract The synthesis and characterization of two novel pyrazole-functionalized chelating polyme... more Abstract The synthesis and characterization of two novel pyrazole-functionalized chelating polymers are reported. Functionalization of p-aminomethyl substituted poly (styrene-co-divinylbenzene) was effected by treatment with 3, 5-dimethyl-1-hydroxymethylpyrazole (product: LDp) and 1-hydroxymethylpyrazole (product: LPz), respectively. For LDp a chelating group with one dimethylpyrazole per amine nitrogen resulted; in the case of LPz both amine hydrogen atoms were substituted by pyrazole groups. The capacities for Cu 2 ...
Applied Thermal Engineering, 2007
A high temperature high lift solid sorption based heat transformer has been successfully designed... more A high temperature high lift solid sorption based heat transformer has been successfully designed and tested. The sorption reactor concept is based on a tube-fin heat exchanger where the heat exchanging fluids can flow through the hollow fins. The plates were brazed together with porous metal foam that was impregnated with either of the sorbents, LiCl and MgCl 2 . The adsorbate is ammonia. The batch system was tested as to the power delivered at high temperatures, 150-200°C. Peak power at 200°C was about 0.8 kW, the average power about 0.4 kW. The thermal efficiency, COP, was calculated from the experimental results to be 0.11. This is only 40% of the expected theoretical value and can largely be attributed to the thermal mass of the reactor.
ABSTRACT The syntheses and characterization of transition-metal co-ordination compounds containin... more ABSTRACT The syntheses and characterization of transition-metal co-ordination compounds containing the newly synthesized ligand N,N-bis(pyrazol-1-ylmethyl)aminoethane (bpae) are described. The compounds have the general formula [M(bpae)X2](M = Co, Cu, Zn, or Cd; X = Cl, Br, or NO3; M = Ni, X = NO3) and [M (bpae)2]X2(M = Mn, Fe, Co, Ni, Cu, Zn, or Cd; X = BF4; M = Ni or Cu, X = NO3). The compounds have been characterized through their spectra and solution conductance. The coordination geometries have been deduced to be five-co-ordinate and octahedral. The crystal structure of the green compound [Cu (bpae) Br2] has been determined by X-ray analysis. A monoclinic unit cell with space group P21/c, a= 9.500(5), b= 11.142(4), c= 13.897(8)Å, β= 93.58(8)°, and Z= 4 was found. The copper atom has a N3Br2 chromophore in a distorted square-pyramidal geometry. The apical bromide has a distance of 2.6721(5)Å to the copper ion, the equatorial bromide 2.3841(5)Å. Copper–nitrogen distances are 1.940(2) and 1.957(2)Å for the pyrazole nitrogen-donor atoms and 2.1 91(2)Å for the amine nitrogen. This geometry is in accord with the spectroscopic results.
Thermochimica Acta, 2002
Structural, thermodynamic and phase properties in the Na2S–H2O system for application in a chemic... more Structural, thermodynamic and phase properties in the Na2S–H2O system for application in a chemical heat pump have been investigated using XRD, TG/DTA and melting point and vapour pressure determinations. Apart from the known crystalline phases Na2S·9H2O, Na2S·5H2O and Na2S a new phase Na2S·2H2O has been proven to exist. Na2S·12H2O is not a phase but a 3:1 mixture of Na2S and
Heat-driven heat pumps based on the principle of chemisorption have been researched worldwide. Su... more Heat-driven heat pumps based on the principle of chemisorption have been researched worldwide. Such research typically focuses either on fundamental materials properties such as sorption isotherms, thermal conductivity and heat of sorption, or on the development and performance of complete systems. Also at ECN the research shows this typical pattern with publications on the fundamental thermodynamic properties on ammonia reactions of lithium chloride and magnesium chloride together with results on complete systems . However, when trying to connect the material properties to the system's performance, for example by using model calculations, various uncertainties on heat exchanger/sorption reactor level remain. These uncertainties, such as reaction kinetics, heat and mass transfer limitations for given specific geometries and conditions but also effects due to repeated sorption, pose a considerable problem for further development, improvement and scaling up of the system. In order to get a better understanding of the performance of the sorption reactor/heat exchanger design and sorbent bed loading, an experimental setup has been developed. This setup allows measuring the performance of various ammonia-sorbent reactions with various sorption reactor/heat exchanger designs under well-controlled and well-monitored process conditions similar to the heat pump conditions. This setup measures the ammonia uptake and release under well-controlled conditions with temperatures that can be varied from ambient temperature up to 200 o C and ammonia pressures that can be varied between 0.02 to 2 MPa. These conditions can be set independently and repeated at regular time-intervals. Besides mass-flow meters, pressure and temperature sensors, the setup also contains an endoscope to observe the macroscopic structural changes in the material during uptake and release of ammonia. After initial testing, the setup is now ready for the first experiments on different heat exchanger designs and sorbent materials. The paper includes a description of the setup and the first experimental results. P reaction -oil average [W] P netto oil [W] Energy balans [kJ] Time [h:mm:ss] Power [W] Energy balans [kJ]
ChemInform
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Proceedings of the International Symposium on Innovative Materials for Processes in Energy Systems 2010, 2010
Heat pumps type II can be used for upgrading industrial waste heat to above pinch temperatures, w... more Heat pumps type II can be used for upgrading industrial waste heat to above pinch temperatures, with a typical lift from 130 o C to 180 o C. At ECN such a heat pump is developed based on the reaction of ammonia with lithium chloride and magnesium chloride as respectively the low and high temperature salt. The thermodynamic properties of these salts are required to determine temperature lift and coefficient of performance. This paper presents the behavior of the low temperature salt, lithium chloride, under typical working conditions with temperatures ranging from ambient to 150°C and ammonia pressures ranging from 0.3 to 30 bars. Measurements using an HPDSC, an autoclave and a custom-made ammonia pressure cell have been conducted to determine the pressure-temperature lines and their corresponding enthalpy and entropy values for lithium chloride ammonia complexes. The results show a direct transformation of lithium chloride mono-ammonia to lithium chloride tri-ammonia complex for ammonia pressures up to 4 bars and temperatures up to 90°C. At higher temperatures and pressures a stable, intermediate ammonia complex, lithium chloride di-ammonia complex, is formed. Under these conditions also a liquid phase has been observed. The latter can greatly affect the heat pump performance, both positive (no lattice degradation) as negative (escape from matrix, form impenetrable film).
Ninth International IBPSA Conference, …, 2005
In a survey recently conducted by ECN and the University of Utrecht in The Netherlands [Visscher,... more In a survey recently conducted by ECN and the University of Utrecht in The Netherlands [Visscher, Oonk et al, 2004]), several potential thermo chemical materials (TCM's) for seasonal storage of solar heat were determined. This first selection was performed on literature data and a set of selection criteria alone. A further selection was performed by a simulationand-comparison procedure between storage materials in a building simulation environment, with a hot water store as a reference case. In this way a few TCM's were identified that may offer chances for development of a new autonomous energy storage system with an effective energy storage density that is at least one order of magnitude larger than that of a hot water store.
Thermochimica Acta, 2002
Structural, thermodynamic and phase properties in the Na 2 S-H 2 O system for application in a ch... more Structural, thermodynamic and phase properties in the Na 2 S-H 2 O system for application in a chemical heat pump have been investigated using XRD, TG/DTA and melting point and vapour pressure determinations. Apart from the known crystalline phases Na 2 SÁ9H 2 O, Na 2 SÁ5H 2 O and Na 2 S a new phase Na 2 SÁ2H 2 O has been proven to exist. Na 2 SÁ 1 2 H 2 O is not a phase but a 3:1 mixture of Na 2 S and Na 2 SÁ2H 2 O, presumably stabilised by very slow dehydration kinetics. The vapour pressure-temperature equilibria of the sodium sulphide hydrates have been determined and a consistent set of thermodynamic functions for these compounds has been derived. XRD measurements indicate the topotactic character of the transitions between the hydration states. #
Journal of Power Sources, 1992
ABSTRACT At the Netherlands Energy Research Foundation, ECN, two approaches to the molten-carbona... more ABSTRACT At the Netherlands Energy Research Foundation, ECN, two approaches to the molten-carbonate fuel cell (MCFC) cathode lifetime problem have been investigated. In the first approach, efforts have been made to reduce the dissolution rate of the state-of-the-art NiO material by means of electrolyte additives. Thus far, it has been possible to obtain a reduction of c. 50% using alkaline-earth oxides or carbonates. The second approach is the development of alternative materials with good performance and very low dissolution rate, suitable to replace NiO. In this respect LiCoO2 is a promising candidate. In addition to a good in-cell behaviour, this material has a dissolution rate which is almost an order of magnitude lower than that of NiO, and its solubility shows favourable gas pressure dependences. In order to explain the significant differences in NiO, LiCoO2 and LiFeO2 performance, porous electrode modelling has been started. Preliminary results indicate that intrinsic materials properties, i.e., catalytic activity and electrical conductivity, play a crucial role in the observed polarization behaviour.
Journal of Power Sources, 2000
The polymer electrolytes are promising materials for the ever-growing need for high energy densit... more The polymer electrolytes are promising materials for the ever-growing need for high energy density power sources for power and traction applications. With an emphasis on lithium batteries, the field of polymer electrolytes has gone through a sort of three stages; dry solid systems, polymer gels, and polymer composites. The 'polymer gels' and the 'polymer composites', the former incorporating organic solvents, have shown room temperature conductivities as high as 10 y3 S cm y1 .The 'dry solid systems' presently suffer from poor ionic Ž y5 y1 . conductivities ; 10 S cm at 208C , but are safer than the former due to absence of any organic solvent which can cause environmental hazards. In the area of electrode systems, one can notice quite good performances by the organo-sulfur polymers as Ž .
Journal of Physics: Conference Series, 2012
ABSTRACT The characterization of the structural, compositional and thermodynamic properties of Mg... more ABSTRACT The characterization of the structural, compositional and thermodynamic properties of MgSO4.7H2O and MgCl2.6H2O has been done using in-situ X-ray Diffraction and thermal analyses (TG/DSC) under practical conditions for seasonal heat storage (Tmax=150°C, p(H2O)=13 mbar). This study showed that these two materials release heat after a dehydration/hydration cycle with energy densities of 0.38 GJ/m3 for MgSO4.7H2O and 0.71 GJ/m3 MgCl2.6H2O. The low heat release found for MgSO4.7H2O is mainly attributed to the amorphization of the material during the dehydration performed at 13 mbar which reduces its sorption capacity during the rehydration. MgCl2.6H2O presents a high energy density which makes this material interesting for seasonal heat storage in domestic applications. This material would be able to fulfil the winter heat demand of a passive house estimated at 6 GJ with a packed bed reactor of 8.5 m3. However, a seasonal heat storage system built with this material should be carefully set with a restricted temperature at 40°C for the hydration reaction to avoid the liquefaction of the material at lower temperature which limits its performances for long term storage.
Journal of The Electrochemical Society, 2002
Journal of The Electrochemical Society, 1992
European Polymer Journal, 1988
Abstract The synthesis and characterization of two novel pyrazole-functionalized chelating polyme... more Abstract The synthesis and characterization of two novel pyrazole-functionalized chelating polymers are reported. Functionalization of p-aminomethyl substituted poly (styrene-co-divinylbenzene) was effected by treatment with 3, 5-dimethyl-1-hydroxymethylpyrazole (product: LDp) and 1-hydroxymethylpyrazole (product: LPz), respectively. For LDp a chelating group with one dimethylpyrazole per amine nitrogen resulted; in the case of LPz both amine hydrogen atoms were substituted by pyrazole groups. The capacities for Cu 2 ...
Applied Thermal Engineering, 2007
A high temperature high lift solid sorption based heat transformer has been successfully designed... more A high temperature high lift solid sorption based heat transformer has been successfully designed and tested. The sorption reactor concept is based on a tube-fin heat exchanger where the heat exchanging fluids can flow through the hollow fins. The plates were brazed together with porous metal foam that was impregnated with either of the sorbents, LiCl and MgCl 2 . The adsorbate is ammonia. The batch system was tested as to the power delivered at high temperatures, 150-200°C. Peak power at 200°C was about 0.8 kW, the average power about 0.4 kW. The thermal efficiency, COP, was calculated from the experimental results to be 0.11. This is only 40% of the expected theoretical value and can largely be attributed to the thermal mass of the reactor.
ABSTRACT The syntheses and characterization of transition-metal co-ordination compounds containin... more ABSTRACT The syntheses and characterization of transition-metal co-ordination compounds containing the newly synthesized ligand N,N-bis(pyrazol-1-ylmethyl)aminoethane (bpae) are described. The compounds have the general formula [M(bpae)X2](M = Co, Cu, Zn, or Cd; X = Cl, Br, or NO3; M = Ni, X = NO3) and [M (bpae)2]X2(M = Mn, Fe, Co, Ni, Cu, Zn, or Cd; X = BF4; M = Ni or Cu, X = NO3). The compounds have been characterized through their spectra and solution conductance. The coordination geometries have been deduced to be five-co-ordinate and octahedral. The crystal structure of the green compound [Cu (bpae) Br2] has been determined by X-ray analysis. A monoclinic unit cell with space group P21/c, a= 9.500(5), b= 11.142(4), c= 13.897(8)Å, β= 93.58(8)°, and Z= 4 was found. The copper atom has a N3Br2 chromophore in a distorted square-pyramidal geometry. The apical bromide has a distance of 2.6721(5)Å to the copper ion, the equatorial bromide 2.3841(5)Å. Copper–nitrogen distances are 1.940(2) and 1.957(2)Å for the pyrazole nitrogen-donor atoms and 2.1 91(2)Å for the amine nitrogen. This geometry is in accord with the spectroscopic results.