In this paper, the load-carrying capacity, power losses and stiffness of disk-type hydrostatic thrust bearings including the case of eccentric loading are discussed theoretically. The numerical analysis method is established based on a two-dimensional elastohydrostatic problem with an elastic deformation model, which is extended to adapt it for a non-axisymmetric load acting on the thrust bearing. The bearing is made of a combination of stainless steel/stainless steel and stainless steel/plastics. For the elastic materials, the maximum stiffness derived from, i.e., minimum film thickness is, larger than that of the rigid material in the range of a large ratio of pocket pressure and a hydrostatic balance ratio of over unity, which is defined as the ratio of the load to the maximum hydrostatic load-carrying capacity. The maximum load-carrying capacity and minimum power loss can exist in the domain of the hydrostatic balance ratio over unity for the case of the bearing consisting of elastic/rigid materials, in comparison with that composed of the same rigid materials. For the case of water, the power loss due to leakage flow is slightly larger but that due to frictional torque is much smaller than that in the case of hydraulic oil. Then, the total power loss is much smaller than that of hydraulic oil. 相似文献
1. 1. System design optimization and validation for single-speed heat pump by S.K. Fischer and C.K. Rice, Oak Ridge National Laboratories.
2. 2. Analysis of on/off cycling for an air-to-air heat pump operating in the heating mode by W.A. Miller, Oak Ridge National Laboratories.
3. 3. Field measured cycling, frosting and defrosting losses for a high efficiency air source heat pump by V.D. Baxter and J.C. Moyers, Oak Ridge National Laboratories.
4. 4. Design and available energy analysis of a heating-only residential heat pump for the Western Pacific Northwest by D.E. Elger, C.M. Reistad and S. Lang, Oregon State University.
5. 5. A study of heat pump service life by Nance C. Lovvorn, Alabama Power Company and Carl C. Hiller, Electric Power Research.
Résumé
1. 1. Optimisation de la conception des systèmes et application à la pompe à chaleur à une seule vitesse;
2. 2. analyse du cycle par tout ou rien d'une pompe à chaleur air-air fonctionnant en mode de chauffage;
3. 3. pertes en fonctionnement cyclique, par givrage et dégivrage mesurées sur place pour une pompe à chaleur de grand rendement dont la source est l'air;
4. 4. conception et analyse de l'énergie disponible d'une pompe à chaleur uniquement pour le chauffage de locaux résidentiels sur la côte du Pacifique nord-ouest occidental;
5. 5. étude de la durée de vie d'une pompe à chaleur.
Les noms et les addresses des auteurs se trouvent dans le sommaire anglais. 相似文献
This paper presents a new computerized procedure for dealing with the design of horizontal ground heat exchangers (HGHE). The computer program is based on the transient model of coupled nonlinear partial differential equations governing heat and mass flow in soils. The model is two-dimensional and delineates the operation of ground heat storage with the HGHE and such phenomena as freezing/thawing and drying/rewetting of soil moisture. Comprehensive climatological data, such as ambient temperature, solar radiation, wind velocity, rainfall, snowfall, snow characterstics, and water vapour pressure is used to simulate conditions at the ground surface over any required length of time. The package can be applied to any geographical location by changing climatic and soil data input. The designer has the possibility of selecting any of 12 types of soils from sand to clay, 12 commercial heat pumps, nine different configurations of the HGHE, 16 plastic pipes for ground coils, and 13 ground coil fluids. The program, however, does not calculate the length of the HGHE but it evaluates the thermodynamic performance of a ground heat pump system and provides comprehensive data on thermal and hydraulic conditions in ground heat storage. The length of the ground heat exchanger is obtained from a line source theory model or from site dimensions and pipe spacing. Computed results for ground heat exchanger operation correlate fairly well with experimental data. Simulation of temperature and moisture content in the ground for natural conditions (no heat extraction/deposition) showed a fair agreement with field data. The entire computer program is user-friendly, interactive, menu-driven, and written in FORTRAN 77. 相似文献
A vibrating U-tube apparatus has been developed for determining the densities of pure fluids and fluid mixtures at 10-200 MPa and 323-773 K. Measured parameters areP,T, andr (period of vibration). Fluids are injected into the U-tube at constantP andT. Three or more reference fluids are used to calibrate the response of the instrument. Fluid mixtures are produced by pumping pure fluids into T-junctions on the upstream side of the U-tube using high accuracy syringe pumps. An automated syringe pump is used to maintainP at setpoint ±0.01 MPa.T is controlled to ±0.01 K using a closed-loop, electronic signal amplification/feedback system. For mixtures, a statistically significant number of measurements of r are obtained to account for the effects of small heterogeneities in fluid composition (generally <0.005X;). Typically, density data for 15 fluids can be obtained in a 6- to 8-h period. Considering all of the potential sources of error in the experimentation, conservative estimates of uncertainty are as follows:P, ±0.02 MPa;T, ±0.05 K;p (pure fluids), ±0.0005g.cm–3; andp (fluid mixtures), ±0.0005-0.0010g-cm–3.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A. 相似文献
A cooling cycle with He II convection driven by self-sustained fountain effect pumps is being investigated. Special attention is drawn to the problem of heat transfer at both ends of the superfilter of this loop. The heat exchanger requirements are derived from theoretical considerations on the degradation of the cooling characteristic effected by non-perfect heat exchangers. A shell and tube type heat exchanger, optimized for the warm end of the filter has been operated in this loop with a thermal load of up to 9 W, with 2.8 g s−1 maximum helium flow rate and with inlet temperatures between 1.8 and 3.4 K. Its performance is well described by computations. A different heat exchanger design with finned Cu walls is suggested for the cold end of the pump. Some considerations on its optimization are given. 相似文献