Electrocaloric (EC) cooling is an emerging technology that has broad potential to disrupt conventional air conditioning and refrigeration as well as electronics cooling applications. EC coolers can be highly efficient, solid state, and compact; have few moving parts; and contain no environmentally harmful or combustible refrigerants. We report a scalable, high-performance system architecture, demonstrated in a device that uses PbSc0.5Ta0.5O3 EC multilayer ceramic capacitors fabricated in a manufacturing-compatible process. We obtained a system temperature span of 5.2°C and a maximum heat flux of 135 milliwatts per square centimeter. This measured heat flux is more than four times higher than other EC cooling demonstrations, and the temperature lift is among the highest for EC systems that use ceramic multilayer capacitors.

We present a novel electrochemical method for separating salt from water in a practical, energy-efficient manner: SUPER (ShUttle-Promoted Electrolyte Removal). SUPER combines elements from redox flow batteries and conventional electrodialysis: a redox shuttle in a four-chambered cell architecture drives ion motion at very low voltages and energy consumption without splitting water, uses no electrocatalysts, and can be salt-agnostic. As exemplified by NaCl, we demonstrate salt removal at a gravimetric specific energy consumption (SEC) as low as 0.046 kWh/kg NaCl transported, which is equivalent to producing water at drinkable salinity (<0.5 parts per thousand [ppt] NaCl) at a volumetric SEC of 1.58 kWh/m(3) in the absence of electroosmotic or osmotic losses. When operating at reasonably high current densities and accounting for these losses, we demonstrate extensive single-stage desalination of simulated seawater (35 -> 0.192 ppt NaCl) at a volumetric SEC of 4.91 kWh/m(3), as well as complete desalination of concentrated brine (203.8 -> 0.192 ppt NaCl) over seven stages at a specific energy consumption of 84.37 kWh/m(3). In addition to its use in seawater desalination, SUPER is capable of efficiently desalting concentrated brines that are not currently possible to treat with nonthermal methods.

The first-order magnetic transition material LaFeSiMn(H) is used to create multi-stage regenerators to investigate the importance of regenerator and magnet design on magnetocaloric refrigeration performance. Aspect ratio, magnetic field strength, particle size, and staging are varied while keeping overall span and material mass at a constant level. Tests carried out on these regenerators show that the regenerator and magnetic systems play a key role in determining the performance of a magnetocaloric refrigerator. A one-dimensional numerical machine model using both measured material data and data reconstructed from a mathematical material model is used to predict test results. The machine model and material model make predictions with less than 5% average error over the range of experimental parameters.

First-order phase transition magnetocaloric materials in multi-stage regenerators are attractive for magnetocaloric refrigeration because of their relatively high available power and the potential for the use of low-cost elements such as iron in their production. In this work a model is used to represent the thermodynamic properties of magnetocaloric materials allowing the magnetocaloric materials to be fully parameterized for the first time. A numerical model is used to carry out a large study including the material parameters and the parameters that describe magnetocaloric machines and their operation. A unique method of evaluating material refrigeration capacity is introduced and used to normalize material inputs. The results are analyzed both in terms of the direct impact of the material parameters and the interactions between machine and material parameters on performance. It was found that machine cooling power was maximized for the cases with the largest adiabatic temperature changes. It was also found that many machine parameters and material parameters interact when determining the performance of a machine. This suggests that materials and machine research would benefit from a closer collaboration.

The use of new mathematical models to represent first-order magnetocaloric materials is reported. Three mathematical models with differing strengths and weaknesses are assessed. The material models are implemented in a numerical model to predict the cyclical performance of a magnetocaloric regenerator. Predictions using both measured and modeled material are compared. A prototype is used to confirm the predictions of the model as well as confirm performance trends related to the variables being investigated. The numerical model with measured and mathematically represented materials shows good correlation to experimental tests. The result is a new and useful method of representing magnetocaloric materials that can accurately predict results over a range of cyclical parameters.

The design and preliminary results of an active magnetic refrigeration prototype for room temperature cooling applications are investigated. The physical prototype along with its operational and measurement envelopes are described. General design goals included: A wide range of cycle parameter control, independent fluid and magnetic circuits, extensive measurement capability, and compact overall design. An initial set of measurements has been made with Gadolinium particulate of an industrial purity. The maximum no-load span recorded was 21K and the maximum power recorded was 26W at a span of 1K. Additionally, three different cyclical parameters have been varied to help determine the optimal cycle for such a machine. The unique modularity and control of this system will allow for a detailed understanding of the operation of commercial active magnetic regeneration designs.

While there have been extensive studies on thermofluid characteristics of different magnetocaloric refrigeration systems, a conclusive optimization study using non dimensional parameters which can be applied to a generic system has not been reported yet. In this study, a numerical model has been developed for optimization of active magnetic refrigerator (AMR). This model is computationally efficient and robust, making it appropriate for running the thousands of simulations required for parametric study and optimization. The governing equations have been non-dimensionalized and numerically, solved using finite difference method. A parametric study on a wide range of non-dimensional numbers has been performed. While the goal of AMR systems is to improve the performance of competitive parameters including COP, cooling capacity and temperature span, new parameters called "AMR performance index-1" have been introduced in order to perform multi objective optimization and simultaneously exploit all these parameters. The multi-objective optimization is carried out for a wide range of the non-dimensional parameters. The results of this study will provide general guidelines for designing high performance AMR systems.

Presented is a discussion of specification for magnetocaloric materials (MCM) when addressing the magnetocaloric effect (MCE). Inferences about specification parameters and how they impact machine performance are made from a machine producer's point of view. A one dimensional model is used to quantify the impact of specifications on machine performance. This specification and impact study should help to guide future machine design and material production efforts.