Multistation refrigeration system

A closed cycle refrigeration (CCR) system is disclosed for providing cooling at different parts of a maser. The CCR includes a first station for cooling the maser's parts, except the amplifier portion, to 4.5 K. The CCR further includes means with a 3.0 K station for cooling the maser's amplifier to 3.0 K and, thereby, increases the maser's gain and/or bandwith by a significant factor. The means which provide the 3.0 K cooling include a pressure regulator, heat exchangers, an expansion valve, and a vacuum pump, which coact to cause helium, provided from a compressor, to liquefy and thereafter expand so as to vaporize. The heat of vaporization for the helium is provided by the maser amplifier, which is thereby cooled to 3.0 K

Improved cryogenic refrigeration system

Two-position shuttle valve simplifies valving arrangement and crank-shaft configuration in gas-balancing and Stirling-cycle refrigeration systems used to produce temperatures below 173 degrees K. It connects the displacer and regenerator alternately to the supply line or the return line of the compressor, and establishes constant pressure on the drive piston

Ten degree Kelvin hydride refrigerator

A compact hydride absorption refrigeration system with few moving parts for 10 Kelvin operation is disclosed and comprises liquid hydrogen producing means in combination with means for solidifying and subliming the liquid hydrogen produced. The liquid hydrogen is sublimed at about 10 Kelvin. By using a symmetrical all hydrogen redundant loop system, a 10 Kelvin refrigeration system can be operated for many years with only a fraction of the power required for prior art systems

Investigation and optimisation of commercial refrigeration cycles using the natural refrigerant CO2

This thesis was submitted for the degree of Doctor of Engineering and awarded by Brunel University.With tighter regulations on the use of Hydroflurocarbons (HFCs) due to their high GWP (Global Warming Potential), many supermarket operators are looking for alternative refrigerants. To contribute to this, the objectives of this thesis are to investigate the practicality, environmental benefits and economic viability of an all-CO2 transcritical refrigeration system suitable for small supermarkets. Whilst the environmental benefits of using CO2 as a refrigerant are clear, there is rather limited practical and technical knowledge on the design and operation of these systems. In this work, simulation models of a transcritical ‘booster’ CO2 refrigeration system have been developed to investigate and evaluate its performance against that of a traditional HFC system. The models were verified using test results from an experimental CO2 system built at Brunel University. To evaluate the performance of the CO2 refrigeration system in the field, energy data from a real supermarket employing a HFC refrigeration system was used for energy simulations. The results demonstrate that the annual energy consumption of the CO2 refrigeration system in a small supermarket in Northern Ireland would be equivalent to that of a typical HFC refrigeration system. However, the low GWP of CO2 will result in a 50% reduction in the combined direct and indirect CO2 emissions over the operational life of the system assuming an annual leakage rate of 15%. Northern Ireland has a high number of small supermarkets due to its rural population, approximately 615. The CO2 system presented in this research could replace the existing R404A systems in these small supermarkets resulting in emissions reduction of up to 188,752 tCO2e. This research has developed selection techniques and criteria to be considered by supermarket designers and operators when developing national strategies for the eventual phase-out of HFC refrigerants in all supermarket sizes. The validated simulation models developed in this research combined with the detailed geographical and refrigeration load ratio analysis presented, will provide valuable information that will assist system designers and operators in the efficient design and optimisation of CO2 technology for small supermarkets.This study was funded by the Engineering and Physical Sciences Research Council and Shilliday Refrigeration

Satellite refrigeration study. Part II TECHNICAL analysis

Low temperature refrigeration system for satellite mounted infrared sensor coolin

Evaluation of absorption cycle for space station environmental control system application Interim report

Zero-gravity absorption refrigeration system design and performance testing for space station environmental control applicatio

Ultra-high temperature stability Joule-Thomson cooler with capability to accomodate pressure variations

A Joule-Thomson cryogenic refrigeration system capable of achieving high temperature stabilities in the presence of varying temperature, atmospheric pressure, and heat load is provided. The Joule-Thomson cryogenic refrigeration system includes a demand flow Joule-Thomson expansion valve disposed in a cryostat of the refrigeration system. The expansion valve has an adjustable orifice that controls the flow of compressed gas therethrough and induces cooling and partial liquefaction of the gas. A recuperative heat exchanger is disposed in the cryostat and coupled to the expansion valve. A thermostatically self-regulating mechanism is disposed in the cryostat and coupled to the J-T expansion valve. The thermostatically self-regulating mechanism automatically adjusts the cross sectional area of the adjustable valve orifice in response to environmental temperature changes and changes in power dissipated at a cold head. A temperature sensing and adjusting mechanism is coupled to a cold head for adjusting the temperature of the cold head in response to the change in heat flow in the cold head. The temperature sensing and adjusting mechanism comprises a temperature sensitive diode, a wound wire heater, and an electrical feedback control circuit coupling the diode to the heater. An absolute pressure relief valve is interposed between the output of the cryostat and an exhaust port for maintaining a constant exhaust temperature in the refrigerating system, independent of the changes in atmospheric pressure

Thermal control for storage of cryogenic propellants in a common-bulkhead tank: A concept

Simple, reliable ground-hold refrigeration system for common-bulkhead tank meets design criteria and objectives for ground-hold of oxygen difluoride and diborane. System is failsafe and malfunctions can be rectified without interruption of basic system functions

Stochastic Analysis of Synchronization in a Supermarket Refrigeration System

Display cases in supermarket systems often exhibit synchronization, in which the expansion valves in the display cases turn on and off at exactly the same time. The study of the influence of switching noise on synchronization in supermarket refrigeration systems is the subject matter of this work. For this purpose, we model it as a hybrid system, for which synchronization corresponds to a periodic trajectory. Subsequently, we investigate the influence of switching noise. We develop a statistical method for computing an intensity function, which measures how often the refrigeration system stays synchronized. By analyzing the intensity, we conclude that the increase in measurement uncertainty yields the decrease at the prevalence of synchronization.Comment: In Proceedings HAS 2014, arXiv:1501.0540