A simulation model for the CO2 heat pump water heater was developed and validated in this study. Component models of the gas cooler, evaporator, compressor, and expansion valve were constructed with careful consideration for the heat transfer performances. To validate the simulation model, experiments were carried out using an actual CO2 heat pump water heater (water heating capacity: 22.3 kW; ...

PURPOSE The aim of the present study was to assess the influence of pre-treatments of zirconia by sandblasting and/or heat treatment on the flexural strength of zirconia and debonding/crack-initiation strength of porcelain-veneered zirconia ceramic. MATERIALS AND METHODS Zirconia ceramic specimens were divided into four groups according to treatment (grinding as controls, sandblasting, heat t...

In this paper, performance analysis of a hybrid photovoltaic-thermal (PV/T) greenhouse air heater and dryer has been carried out. Analytical expressions have been developed for • greenhouse air temperature, instantaneous and overall energy and exergy efficiencies for without load and • instantaneous exergy efficiency with load under forced mode operation. An experimental validation has been car...

Transient nucleate pool boiling experiments using R113 are conducted for short times in microgravity and in earth gravity with different heater surface orientations and subcoolings. The heating surface is a transparent gold film sputtered on a quartz substrate, which simultaneously provides surface temperature measurements and permits viewing of the boiling process from beneath. For the microgr...

Recent research progress in the area of nano/micro scale nucleate boiling is reviewed and an up-to-date summary is provided with a focus on the advances of fundamental boiling physics. This review examines nano/micro scale pool boiling experimental and theoretical/numerical work reported in the open literature. On the experimental side, the topics covered are moving contact line, critical heat ...

An experimental study was conducted to extend the operation of a graphite resistance nitrogen heater to pressures dbove the 1000 psl previously obtained. Using a somewhat modified design, a single pass spiral heater element was fabricated and tested at 5000 psl and 5000 R. Test runs of 5 to 15 minutes were carried out with total operating times at elevated temperatures and pressure exceeding se...

This study compares the performance of five electrical water heater models in the TRNSYS environment. The main capabilities, modeling assumptions and performance of the models are first assessed using an intermodel comparison. The main criteria for comparison are: domestic hot water supply temperature, power demand (time-dependent profile and overall energy use) and vertical temperature distrib...

We report on measurements of thermopower oscillations vs magnetic field in diffusive Andreev interferometer. Upon the increase of the dc current applied to the heater electrodes, the amplitude of these oscillations first increases then goes to zero as one would expect. Surprisingly the oscillations reappear at yet higher heater currents with their phase being π-shifted compared to low current v...

Heat transport in the quantum Hall regime is investigated using micron-scale heaters and thermometers positioned along the edge of a millimeter-scale two dimensional electron system (2DES). The heaters rely on localized current injection into the 2DES, while the thermometers are based on the thermoelectric effect. In the nu=1 integer quantized Hall state, a thermoelectric signal appears at an e...

It is proposed to apply high-temperature superconducting (HTS) tape in the coil windings for induction heaters for aluminium or copper extrusion billets. The potential for efficiency improvements is substantial, as conventional copper coil induction heaters rated for up to around 1 MW operate with an overall efficiency of typically only 50–60%. The efficiency of a HTS induction heater depends v...