Handboek warmtepompen voor de gebouwde omgeving

Aankondiging van het Handboe

Éditorialistes Invités. Lombalgie: le moment est venu de s’éngager dans l’éaboration de lignes directrices pour la pratique.

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Energy labelling of air to air heat pumps

In July of 1998 a proposal for a methodology for energy labelling of small sized air to air heat pumps was presented to the EC. This proposal was prepared by TNO-MEP, in co-operation with BSRIA (UK), CETIAT (F) and DTI (Dk) under the EC SAVE programme. An energy label gives information to the public as to the energy efficiency of a certain appliance in relation to the average energy efficiency of similar appliances. An energy label is not an energy efficiency standard - which prohibits the trade in inefficient appliances (such as present in countries outside the EC). On the energy labels already existing in the EC, the efficiency is expressed by means ofa lettering system (class A:efficient to class G: inefficient). The proposed energy labelling methodology covers in fact both air to air heat pumps up to a heating capacity of 14 kW and (reversible and cooling only) air conditioners up to a cooling capacity of 12 kW. The proposed methodology first groups the appliances into product categories, and then compares the energy efficiency of a specific appliance to the market average efficiency for that product category to arrive at the appropriate energy efficiency class for the appliance. To define efficiency, COP and EER values at full load have been used. All underlying data (capacities and energy consumption) are based on European standards EN 255 an EN 814. The proposal furthermore recommends to evaluate the efficiency for inverter driven units at part load, and to draw up a test standard for measurements at part load. The proposal was prepared in co-operation with EUROVENT, the European Committee of Air Handling and Air Refrigerating Equipment manufacturers

Development of an electro-osmotic heat pump

The majority of heat pumps and refrigerators is driven by a mechanical compressor. Although they usually function very well, the search for new and in some cases better heat pumping concepts continues. One of the topics in this field is the development of an electro-osmotic heat pump. As each electricity driven heat pumping technique, electro-osmosis is related to a power generation equivalent: the fuel cell. By applying a direct current voltage over the compression unit a pressure difference can be realised, leading to a heat pumping effect. Since 1995 TNO MEP has been working on this concept. After a quick theoretical scan, it was concluded that the concept might work. This quick scan was followed in 1996 and 1997 by experimental work with the aim to demonstrate the compression function. As it proved to be successful a new test rig is being built in 1998. It will be evaluated in the next months with respect to capacities, Coefficient of Performance and part load behaviour. Besides the influence of input parameters will be determined. Of course the concept has a number of advantages over conventional compression machines. An electro-osmotic heat pump has no moving parts, can be very compact, does not make any noise and uses an environmentally friendly refrigerant. Attractive applications may be small air-conditioners, for example for cars or buses, heat pumps for combined heating and cooling and specialities for small cooling capacities

Flammable refrigerants

Hydrocarbons are promising alternatives for CFC, HCFC and HFC refrigerants. Due to their flammable nature, safety aspects have to be considered carefully. The world-wide situation concerning acceptability and practical application of flammable refrigerants is becoming more and more complex and confusing. Quantification of the risks of using flammable refrigerants in specific applications is the only way to make the situation clear and to discuss this topic on the basis of facts and figures. Several Quantitative Risk Assessments (QRA) have been carried out by TNO, resulting in risk figures to be compared with generally accepted risk criteria. In addition, risk reducing measures may be evaluated by using the same kind of QRA's. The example QRA's carried out for the cooling system of a bulk milk tank and for a residential heat pump, show acceptable risk levels, as long as the proper safety measures are applied. Other QRA's for several applications (domestic refrigerators, air dehumidifiers, automotive air-conditioning etc.) containing up to a few kilograms of hydrocarbon refrigerant confirm these results. Several national, European and international (draft) standards and guidelines are available, almost always being inconsistent or conflicting. Most of them are based on refrigeration expertise and experience, and not on a quantification of the risks. A Working Group of CEN/TC 182 currently identifies and quantifies the risks of flammable refrigerants, creating a solid basis for a revision of the European safety standard for refrigerating systems and heat pumps

Evidence-based rehabilitation medicine and physiotherapy: a critical appraisal.

Contains fulltext : 70347.pdf (publisher's version ) (Open Access

Modelling of ground source heat exchanger performance

The ground presents a practical heat source for small scale heat pump applications, such as single family dwellings. Where little space is available, vertical ground source heat exchangers (GSHX) extending to a depth of 15 - 100 metres can be used. The number of pipes, and their length, is of great importance to the temperature at which the heat is extracted, and consequently to the heat pump COP. In the design phase of a GSHX system, computer programs like EED (Earth Energy Designer) can be used to calculate the number and length of GSHX pipes needed. To simulate actual (dynamic) behaviour of the GSHX system, more powerful computer codes are needed. The "Bodemtix" program, developed by TNO - MEP from earlier simulation programs [1,2] is especially suited to perform calculations on dynamic behaviour of GSHX applications. The program can be used to calculate - based on an hourly demand pattern - the temperature of the medium circulating inside the heat exchanger, for periods extending up to 25 years. Another additional feature of Bodemtix is, that the program is suited to simulate freezing of the ground surrounding the pipes - which may occur during peak heat demands. A proper simulation at peak heat demands is essential for monovalent systems (heat pumps without additional heating). Furthermore, the program can also make simulations with ground water flow - which is important in the Dutch situation with sandy, wet soils. The Bodemtix program has been validated on the basis of existing and new measurements in the field. The results are quite satisfactory, although in the trajectory of freezing of the ground the differences between measurements and simulation are relatively high. A comparison to other available programs for GSHX calculation shows that Bodemtix results keep the middle between the results of these other programs

Employment status of patients with neuromuscular diseases in relation to personal factors, fatigue and health status: a secondary analysis.

Contains fulltext : 88673.pdf (publisher's version ) (Open Access)OBJECTIVE: To determine the number of employed people in a group of patients with neuromuscular diseases and in 3 separate subgroups (facioscapulo-humeral dystrophy, hereditary motor and sensory neuropathy, and myotonic dystrophy) to investigate any differences in employment status between the patient groups, and to identify factors related to employment status. DESIGN: Cross-sectional study. PATIENTS: A total of 591 patients with neuromuscular diseases participated in the study, 138 with facioscapulo-humeral dystrophy, 135 with hereditary motor and sensory neuropathy, and 318 with myotonic dystrophy. METHODS: Self-report questionnaires, the Checklist Individual Strength (CIS) and the Short Form-36 (SF-36). RESULTS: Of the patients with neuromuscular diseases in the study, 56.7% were employed. Younger age, being male, and higher education contributed significantly to employment status of the neuromuscular diseases group and the hereditary motor and sensory neuropathy and myotonic dystrophy subgroups. Significant between-group differences for employed vs not employed subjects were present in the total neuromuscular diseases group on all subscales of the CIS and SF-36. Factors related to employment status differed for the 3 neuromuscular diseases subgroups. CONCLUSION: More than half of the patients with neuromuscular diseases were employed. Patients with facioscapulo-humeral dystrophy and patients with hereditary motor and sensory neuropathy were more often employed than patients with myotonic dystrophy. Between-group analyses for differences in baseline factors revealed 11 significant factors related to employment. Multivariate logistic analyses revealed 6 factors contributing to employment for the group of patients with neuromuscular diseases.1 januari 201