| 1. |
- Bales, Chris, et al.
(författare)
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TCA Evaluation : Lab Measurements, Modelling and System Simulations
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The study reported here is part of a large project for evaluation of the Thermo-Chemical Accumulator (TCA), a technology under development by the Swedish company ClimateWell AB. The studies concentrate on the use of the technology for comfort cooling. This report concentrates on measurements in the laboratory, modelling and system simulation. The TCA is a three-phase absorption heat pump that stores energy in the form of crystallised salt, in this case Lithium Chloride (LiCl) with water being the other substance. The process requires vacuum conditions as with standard absorption chillers using LiBr/water. Measurements were carried out in the laboratories at the Solar Energy Research Center SERC, at Högskolan Dalarna as well as at ClimateWell AB. The measurements at SERC were performed on a prototype version 7:1 and showed that this prototype had several problems resulting in poor and unreliable performance. The main results were that: there was significant corrosion leading to non-condensable gases that in turn caused very poor performance; unwanted crystallisation caused blockages as well as inconsistent behaviour; poor wetting of the heat exchangers resulted in relatively high temperature drops there. A measured thermal COP for cooling of 0.46 was found, which is significantly lower than the theoretical value. These findings resulted in a thorough redesign for the new prototype, called ClimateWell 10 (CW10), which was tested briefly by the authors at ClimateWell. The data collected here was not large, but enough to show that the machine worked consistently with no noticeable vacuum problems. It was also sufficient for identifying the main parameters in a simulation model developed for the TRNSYS simulation environment, but not enough to verify the model properly. This model was shown to be able to simulate the dynamic as well as static performance of the CW10, and was then used in a series of system simulations. A single system model was developed as the basis of the system simulations, consisting of a CW10 machine, 30 m2 flat plate solar collectors with backup boiler and an office with a design cooling load in Stockholm of 50 W/m2, resulting in a 7.5 kW design load for the 150 m2 floor area. Two base cases were defined based on this: one for Stockholm using a dry cooler with design cooling rate of 30 kW; one for Madrid with a cooling tower with design cooling rate of 34 kW. A number of parametric studies were performed based on these two base cases. These showed that the temperature lift is a limiting factor for cooling for higher ambient temperatures and for charging with fixed temperature source such as district heating. The simulated evacuated tube collector performs only marginally better than a good flat plate collector if considering the gross area, the margin being greater for larger solar fractions. For 30 m2 collector a solar faction of 49% and 67% were achieved for the Stockholm and Madrid base cases respectively. The average annual efficiency of the collector in Stockholm (12%) was much lower than that in Madrid (19%). The thermal COP was simulated to be approximately 0.70, but has not been possible to verify with measured data. The annual electrical COP was shown to be very dependent on the cooling load as a large proportion of electrical use is for components that are permanently on. For the cooling loads studied, the annual electrical COP ranged from 2.2 for a 2000 kWh cooling load to 18.0 for a 21000 kWh cooling load. There is however a potential to reduce the electricity consumption in the machine, which would improve these figures significantly. It was shown that a cooling tower is necessary for the Madrid climate, whereas a dry cooler is sufficient for Stockholm although a cooling tower does improve performance. The simulation study was very shallow and has shown a number of areas that are important to study in more depth. One such area is advanced control strategy, which is necessary to mitigate the weakness of the technology (low temperature lift for cooling) and to optimally use its strength (storage).
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| 2. |
- Delbro, Dick, et al.
(författare)
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Nuclear expression of mu-opioid receptors in a human mesothelial cell line
- 2009
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Ingår i: Autonomic & Autacoid Pharmacology. - : Wiley. - 1474-8665 .- 1474-8673. ; 29:4, s. 165-170
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Tidskriftsartikel (refereegranskat)abstract
- 1 Possibly acting via mu-opioid receptors (MORs), morphine inhibits the formation ofexperimentally induced postoperative abdominal adhesions in rats. Mesothelial cells mayparticipate in adhesion formation by secreting mediators that interfere negatively withfibrinolysis. Morphine may prevent adhesions by inhibiting the release of pro-adhesionmediators from mesothelial cells. This study aimed to investigate whether human mesothelialcells express MOR-1; if so, such could constitute a site of action for morphine in adhesionprevention.2 Cells from Met-5A, a human mesothelial cell line were seeded and prepared forimmunocytochemistry and Western blotting.3 Immunocytochemistry showed MOR-1 expression in mesothelial cells, predominantly in thenuclei. Western blotting showed two bands (c. 35 and 50 kDa) which correspond to thoseobtained with a control lysate from cells known to express MORs. In addition, we foundMOR-1 expression with nuclear and cytoplasmatic localization in biopsies from humanabdominal adhesions.4 The current findings may suggest that morphine could interact directly with mesothelial cellsvia MOR-1 receptors, and thereby modulate adhesion formation, possibly by interfering withthe release of pro-adhesion factors from these cells
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| 3. |
- Fiedler, Frank, et al.
(författare)
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Comparison of carbon monoxide emissions and electricity consumption of modulating and non-modulating pellet and solar heating systems
- 2007
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 31:10, s. 915-930
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Tidskriftsartikel (refereegranskat)abstract
- Emission and electricity consumption are important aspects of a pellet heating system. Low noxious emissions, particularly carbon monoxide, are a measure of a well-performing system. High carbon monoxide emissions are often caused by unnecessary cycling of the burner, poor adjustment of the combustion air and insufficient maintenance. The carbon monoxide output, the thermal performance and the electricity consumption for modulating and non-modulating operation mode have been investigated by simulations of four stoves/boilers as part of combined solar and pellet heating systems. The systems have been modelled with the simulation programme TRNSYS and simulated with the boundary conditions for space heating demand, hot water load and climate data as used in earlier research projects. The results from the simulations show that operating the pellet units with modulating combustion power reduces the number of starts and stops but does not necessarily reduce the carbon monoxide output. Whether the carbon monoxide output can be reduced or not depends very strongly on the reduction of starts and stops and how much the carbon monoxide emissions increase with decreased combustion power, which are in turn dependent on the particular settings of each pellet burner and how the heat is transferred to the building. However, for most systems the modulating operation mode has a positive impact on carbon monoxide emissions. Considering the total auxiliary energy demand, including the electricity demand of the pellet units, the modulating combustion control is advantageous for systems 1 and 4 for the used boundary conditions. The study also shows that an appropriate sizing of the stove or boiler has a huge potential for energy saving and carbon monoxide emission reduction.
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| 4. |
- Fiedler, Frank, et al.
(författare)
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Thermal performance of combined solar and pellet heating systems
- 2006
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Ingår i: Renewable energy. - : Elsevier BV. - 0960-1481 .- 1879-0682. ; 31, s. 73-88
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Tidskriftsartikel (refereegranskat)abstract
- Various pellet heating systems are marketed in Sweden, some of them in combination with a solar heating system. Several types of pellet heating units are available and can be used for a combined system. This article compares four typical combined solar and pellet heating systems. System 1 and 2 with a pellet stove, system 3 with a store integrated pellet burner and system 4 with a pellet boiler. The often lower efficiency of pellet heaters compared to oil or gas heaters increases the final energy demand. Consequently, heat losses of the various systems have been studied. The systems have been modeled in TRNSYS and simulated with parameters identified from measurements. For almost all systems the flue gas losses are the main heat losses except for system 3 where store heat losses prevail. Relevant are also the heat losses of the burner and the boiler to the ambient. Significant leakage losses are noticed for system 3 and 4. For buildings with an open internal design system I is the most efficient solution. Other buildings should preferably apply system 2 or 3. The right choice of the system depends also on whether the heater is placed inside or outside of the heated area. Unlike the expectations and results from other studies, the operation of the pellet heaters with modulating combustion power is not necessarily improving the performance. A large potential for system optimisation exists for all studied systems, which when applied could alter the relative merits of the different system types
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| 5. |
- Nordlander, Svante, et al.
(författare)
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Computer modelling of wood pellet stoves and boilers connected to solar heating systems
- 2006
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Ingår i: Proc on USB of Pellets 2006, 30 May - 1 June, Jönköping, Sweden. - Jönköping, Sweden.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- When optimizing systems for wood pellet and solar heating, there is a need for realistic computer models of stoves and boilers in order to perform simulation studies. The objective of this work was to develop and verify a mathematical model for wood pellet stoves and boilers for use in system simulations with TRNSYS calculating both the energy balance and CO-emissions (carbon monoxide). Laboratory measurements have been carried out on three pellet stoves, one traditional and two with gas-liquid heat exchangers, and four pellet boilers. A mathematical two-node model of a stove was developed and implemented as a TRNSYS component. Parameters were identified for two stoves and three boilers. This new model makes it possible to perform detailed simulations with time steps less than a minute of complete wood pellet heating systems and to derive long term values, such as annual values, of efficiency and emissions for the boiler or stove in a system context under realistic conditions. In addition, parametric studies can be used in order to investigate how different operation principles and system design affect these values. The simulated energy balance of a water jacketed stove investigated in this work agreed well with measured data during both stationary and dynamic conditions.
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| 6. |
- Nordlander, Svante
(författare)
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Maximum concentration for ideal asymmetrical radiation concentrators
- 2005
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Ingår i: Solar Energy. - 0038-092X .- 1471-1257. ; 79:5, s. 566-567
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Tidskriftsartikel (refereegranskat)abstract
- A new relation between the maximum geometric concentration factor C and the angular acceptance interval for asymmetrical ideal non-imaging concentrators is proposed. A generalization of the well-known relation for the two-dimensional case, sin ?c = 1/C where ?c is the acceptance half-angle, results in the proposed relation sin ?2 -sin ?1 = 2/C , where ?1 and ?2 are the angles of the acceptance interval limits relative to the normal of the entrance aperture. The proposed relation is valid for any ideal 2D concentrator, symmetrical or asymmetrical. A proof based on conservation of phase space is provided.
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| 7. |
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| 8. |
- Persson, Tomas, et al.
(författare)
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Electrical savings by use of wood pellet stoves and solar heating systems in electrically heated single-family houses
- 2005
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Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788 .- 1872-6178. ; 37:9, s. 920-929
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates how electrically heated single-family houses can be converted to wood pellets- and solar heating using pellet stoves and solar heating systems. Four different system concepts are presented and system simulations in TRNSYS evaluate the thermal performance and the electrical savings possible for two different electrically heated single-family houses. Simulations show that the electricity savings using a wood pellet stove are greatly affected by the level of comfort, the house plan, the system choice and if the internal doors are open or closed. Installing a stove with a water-jacket connected to a radiator system and a hot water store has the advantage that heat can be transferred to domestic hot water and be distributed to other rooms. Such systems leads to that more electricity can be replaced, especially in houses having a traditional plan. Though it is unnecessary to have too many radiators connected to a stove with a low fraction of energy heating the water jacket. Today's most common control strategy for stoves (the on/off-control) results in unnecessarily high emissions. A more advanced control varying the heating rate from maximum to minimum to keep a constant room temperature reduces the number of starts and stops and thereby the emissions.
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| 9. |
- Persson, Tomas, et al.
(författare)
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Validation of a dynamic model for wood pellet boilers and stoves
- 2009
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; :86
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Tidskriftsartikel (refereegranskat)abstract
- Optimising systems with wood pellet boilers or stoves using simulations requires realistic computer models. The objective of this work was to develop and verify a mathematical model for wood pellet boilers and stoves for use in system simulations with the dynamic simulation programme TRNSYS, calculating both the energy balance and the CO-emissions (carbon monoxide emissions). Laboratory measurements have been carried out and a mathematical two-node model was developed and implemented as a TRNSYS component. Parameters were identified and the model has been compared with measurements. The model shows in general good agreement with measured data, however there are details that could be improved. This involves improved modelling of the dynamic response for boilers with large water volumes and improved modelling of the air factor and the CO-emissions, especially during start and stop conditions. Further improved methodology and accuracy for measuring and parameter identification is recommended.
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| 10. |
- Pettersson, Ann, 1982-, et al.
(författare)
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Expression of the endogenous, nicotinic acetylcholine receptor ligand, SLURP-1, in human colon cancer.
- 2008
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Ingår i: Autonomic & Autacoid Pharmacology. - : Wiley. - 1474-8665 .- 1474-8673. ; 28:4, s. 109-116
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Tidskriftsartikel (refereegranskat)abstract
- 1. Secreted mammalian Ly-6/urokinase plasminogen activator receptor-related protein-1 (SLURP-1) is a recently discovered endogenous ligand at the alpha7 subunit of the nicotinic acetylcholine receptors. Previous reports have shown that SLURP-1 is expressed in normal human keratinocytes seemingly with a pro-apoptotic function. Conversely, such expression was markedly attenuated in transformed cells and it was suggested that the molecule could convey protection against malignant transformation. 2. In this study, we demonstrated the mRNA expression (by RT-PCR) and protein expression (by Western blotting and immunocytochemistry) of SLURP-1 in the human colon cancer cell line, HT-29. 3. Furthermore, we demonstrated the expression of SLURP-1 (by immunohistochemistry) in tumour cells of human colon cancer tissue, and, to a greater extent, in immune and smooth muscle cells of adjacent, macroscopically tumour-free colon tissue. 4. The current findings suggest that SLURP-1 participates in the regulation of gut immune functions and motility, as well as possibly playing a role in colon carcinogenesis/cancer progression.
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