thermal | PartQuest™ Explore

This is a model of an Ember coffee mug -- a battery-powered, state-of-the-art beverage container that controls the temperature of your beverage to keep it at the setpoint you specify for a couple of hours.See https://ember.com/This model simulates the process of filling the mug with a hot liquid and maintaining it at the setpoint until the battery is exhausted. This model includes modeling of the PCM (Phase Change Material). From the measurements used to characterize the actual device, it appears that the PCM contains multiple melting-point materials (see experimental results here: https://www.systemvision.com/design/ember-coffee-mug-2-pcm-experimental-data-0), thus two were included –at melting points of 47C and 52C respectively. The thermal mass of the liquid is modeled by the block with a “coffee cup” symbol. The feedback control is simple proportional gain. The battery is Li-Ion chemistry with a capacity calibrated from measurements on the real-life temperature profile over time – estimated as 5 cells in series (total ~17 V), since the charger voltage was just under 20 V, with 130 milliamp-hour capacity each, for a total of 650 milliamp-hours capacity.The red wires are thermal, with temperature as the across variable and heat flow as the conserved through variable. Black wires are electrical, with voltage as the across variable and current as the conserved through variable. The green wires are directional control signals (modeling the control system variables). The block labeled “Temp” models the temperature sensor, feeding back the temperature to the proportional controller. The block on the far-left in the setpoint, with a step-input from ambient to the desired beverage temperature.

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Ember coffee mug control system heating element

elainet
Designer158531

elainet

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7 years

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Description

This is a model of an Ember coffee mug -- a battery-powered, state-of-the-art beverage container that controls the temperature of your beverage to keep it at the setpoint you specify for a couple of hours.See https://ember.com/This model simulates the process of filling the mug with a hot liquid and maintaining it at the setpoint until the battery is exhausted. This model includes modeling of the PCM (Phase Change Material). From the measurements used to characterize the actual device, it appears that the PCM contains multiple melting-point materials (see experimental results here: https://www.systemvision.com/design/ember-coffee-mug-2-pcm-experimental-data-0), thus two were included –at melting points of 47C and 52C respectively. The thermal mass of the liquid is modeled by the block with a “coffee cup” symbol. The feedback control is simple proportional gain. The battery is Li-Ion chemistry with a capacity calibrated from measurements on the real-life temperature profile over time – estimated as 5 cells in series (total ~17 V), since the charger voltage was just under 20 V, with 130 milliamp-hour capacity each, for a total of 650 milliamp-hours capacity.The red wires are thermal, with temperature as the across variable and heat flow as the conserved through variable. Black wires are electrical, with voltage as the across variable and current as the conserved through variable. The green wires are directional control signals (modeling the control system variables). The block labeled “Temp” models the temperature sensor, feeding back the temperature to the proportional controller. The block on the far-left in the setpoint, with a step-input from ambient to the desired beverage temperature.

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Ember coffee mug control system heating element

Ben_2
Designer135501

Ben_2

Member for

7 years 5 months

61

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Member of the PartQuest Explore team.

Ember coffee mug control system

Darrell
Designer10

Darrell

Member for

11 years

624

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Big fan of VHDL-AMS

Ember coffee mug 2 PCM experimental data

Darrell
Designer10

Darrell

Member for

11 years

624

designs

10

groups

Big fan of VHDL-AMS

Description

This is a model of an Ember coffee mug -- a battery-powered, state-of-the-art beverage container that controls the temperature of your beverage to keep it at the setpoint you specify for a couple of hours.See https://ember.com/The purpose of this model is to calibrate the phase change material (PCM) that is used in the Ember mug. The following experiments were passive -- the Ember mug was powered off during all of these measurements so that the intrinsic characteristics of the materials could be determined.The temperature represented by the node ember_temp_exper is experimental data collected from an actual Ember mug. 350 ml of water at 77.2C was added to the mug and its temperature was measured over several hours.The temperature represented by the node insulated_temp_exper is experimental data collected from an ordinary insulated mug of approximately the same size. 400 ml of water at 77.2C was added to this mug and its temperature was measured over several hours.The difference between these two temperatures shows the effect of the PCM used in the Ember mug. The energy required to melt the PCM causes the Ember mug temperature to drop much more quickly than the ordinary insulated mug. As the water in each cools, however, the PCM energy is recovered, as the temperature drops below the melting point, causing the water temperature in the Ember mug to drop more slowly than the ordinary insulated mug.The thermal network shown here models the thermal characteristics of the Ember mug. This includes the thermal mass for the water, with its Cp, two PCM blocks, thermal impedances, and the ambient temperature. The thermal capacitor is used only the establish the initial conditions at the beginning of the simulation, but could also be used to model the thermal capacitance of the mug body.Two PCMs are used, since the experimental data appears to show two distinct inflection points in the temperature decay.further work:The insulated mug contained 400ml of water, while the Ember contained only 350ml (its max capacity). It would be more meaningful to compare the results of an additional experiment where 350ml of water is used in the insulated mug.

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