This article reviews the progression of refrigerants, from early uses to the present, and then addresses future directions and candidates. The article breaks the history into four refrigerant generations based on defining selection criteria. It discusses displacement of earlier working fluids, with successive criteria, and how interest in some early refrigerants re-emerged, for example renewed interest in those now identified as ‘‘natural refrigerants.’’ The paper examines the outlook for current options in the contexts of existing international agreements, including the Montreal and Kyoto Protocols to avert stratospheric ozone depletion and global climate change, respectively. It also examines other environmental concerns and further international and local control measures. The discussion illustrates how isolated attention to individual environmental issues or regulatory requirements, in contrast to coordinated responses to the several issues together, can result in unintended environmental harm that almost certainly will require future reversals. It identifies pending policy and regulatory changes that may impact the next generation of refrigerants significantly.

http://www.jamesmcalm.com/pubs/Calm%20JM,%202008.%20The%20Next%20Generation%20of%20Refrigerants%20-%20Historical%20Review,%20Considerations,%20and%20Outlook,%20IJR.pdf

The next generation of refrigerants – Historical review, considerations, and outlook

A thin film magnetic head includes an upper shield section, a lower shield section and a magnetoresistance device section between the upper shield section and the lower shield section. The magnetoresistance device section is connected to the upper shield section and the lower shield section through conductive layers. Current flows through the magnetoresistance device section via the upper shield and the lower shield.

Thin film magnetic head

A heat pump system (1) has a refrigerant circuit (20) and a controller (1a), The refrigerant circuit (20) has usage units (5a, 5b) connected to a heat source unit (2), the usage units (5a, 5b) having first usage-side heat exchangers (51a, 51b), and the heat source unit (2) having a heat-source-side heat exchanger (26a, 26b) and a compressor (21). The usage units (5a, 5b) further have second usage-side heat exchangers (151a, 151b). The controller (1a) causes the heat-snurce-side heat exchanger (26a, 26b) to function as an evaporator or as a radiator in accordance with an overall heat load of the usage units (5a, 5b) in a state in which the heating operation for heating the aqueous medium by heat radiation of the refrigerant in the first usage-side heat exchangers (51a, slob) or the cooling operation for cooling the aqueous medium by evaporation of the refrigerant in the second usage-side heat exchangers (151a, 151b) has been set for each of the usage units (5a, 5b).

Heat-pump system

PROBLEM TO BE SOLVED: To provide a high-efficiency heat pump type water heater, hardly causing run-out of hot water and having excellent convenience SOLUTION: This heat pump type water heater includes: a hot water delivery pipe 18, an intermediate hot water delivery pipe 21 and a water supply pipe connected to the upper part, the intermediate part and the lower part, respectively, of a hot water storage tank 5 for storing hot water heated by a hot water supply heat exchanger 2; a bathtub heat exchanger 6 connected between the upper part of the hot water storage tank 5 and a lower part below the upper part and configured to heat the hot water in a bathtub 8 taking the hot water in the upper part of the hot water storage tank 5 as a heat source; and hot water intermediate mixing valves 19, 22 for mixing hot water from the hot water delivery pipe 18, the intermediate hot water delivery pipe 21 and the water supply pipe 17 and adjusting the same to a preset hot water supply temperature, wherein when a hot water request and a bathtub heating request are given at the same time, some or all of hot water from the upper part of the hot water storing tank 5 radiated by the bathtub heat exchanger 6 is directly used for hot water, whereby hot water can be effectively utilized to lower the possibility of run-out of hot water, the amenity and convenience are improved, and since generation of medium temperature water due to mixing of medium temperature water returned from the bathtub heat exchanger 6 and hot water of the hot water storage tank 5 is decreased, the operation efficiency is improved COPYRIGHT: (C)2009,JPO&INPIT

Heat pump type water heater

A heat pump water heater includes: a compressor; a first water-refrigerant heat exchanger; a second water-refrigerant heat exchanger; refrigerant paths capable of forming a refrigerant circuit; and water channels including a flow channel, the flow channel leading hot water that has passed through the second water-refrigerant heat exchanger to the first water-refrigerant heat exchanger The heat pump water heater is able to perform a heating operation In the heating operation, the hot water heated in the second water-refrigerant heat exchanger is fed to the first water-refrigerant heat exchanger and the hot water further heated in the first water-refrigerant heat exchanger is supplied to a downstream side of the water channels The first water-refrigerant heat exchanger is able to be replaced without replacing the second water-refrigerant heat exchanger

Heat pump water heater

A flash water heater using a heat pump includes a heat exchanger in which a refrigerant flow path exchanges heat with a water flow path. Tap water is led directly to the water flow path, and hot water supplied from the water flow path is used. The water heater includes at least one of the following elements: 1) a load setter for setting a heating amount in the heat exchanger, and a heating controller for regulating a heating amount in response to an amount set by the load setter; 2) a heater for heating water flowing through the water flow path in the heat exchanger and water flowing the path before and after the heat exchanger; 3) plural compressors; and 4) plural heat-pump cycles. The water heater is excellent in start-up of hot water temperature when the hot water supply starts, controllability, and efficiency.

Takeshi Watanabe

Papers

Heat pump water heater

Heat pump water device