Model sensor that converts thermal potential difference into electrical potential difference
Sensors
The Thermocouple block represents a thermocouple using the standard polynomial parameterization defined in the NIST ITS90 Thermocouple Database [1]. The voltage E across the device in mV is
E(mV) = c0 + c1*t + ... + cn*t^{n}
where:
ci is the i^{th} element of the Coefficients [c0 c1 ... cn] parameter value.
t is the temperature difference in degrees Celsius between the temperature at the thermal port A and the Reference temperature parameter value.
Note: The equation for voltage across the device as a function of temperature difference is defined in mV. The units of the voltage across the actual device is V. 
The following equation describes the thermal behavior of the block:
$$Q={K}_{d}{t}_{c}\frac{dT}{dt}$$
where:
T is the temperature at port A.
Q is the net heat flow into port A.
K_{d} is the Dissipation factor parameter value.
t_{c} is the Thermal time constant parameter value.
dT/dt is the rate of change of the temperature.
To model the thermocouple in free space:
Connect the thermocouple to the B port of a Simscape™ Convective Heat Transfer block.
Connect the A port of the Convective Heat Transfer block to a Simscape Ideal Temperature Source block whose temperature is set to the ambient temperature.
Set the Area parameter of the Convective Heat Transfer block to an approximate area A_{nom}.
Set the Heat transfer coefficient parameter of the Convective Heat Transfer block to K_{d}/A_{nom}.
The model is based on the following assumptions:
The highorder polynomials this block uses are very sensitive to the number of significant figures used for computation. Use all available significant figures when specifying the Coefficients [c0 c1 ... cn] parameter.
Coefficients [c0 c1 ... cn] are defined for use over a specified temperature range.
This block does not include the additional exponential term that Type K thermocouples use when parameterized for t > 0.
The vector of coefficients c in the equation
that describes voltage as a function of temperature. The default value
is [ 0 0.0054031 1.2593e05 2.3248e08 3.2203e11 3.315e14
2.5574e17 1.2507e20 2.7144e24 ]
. This value specifies
a Type S thermocouple, which is valid in the range 50 to 1064 degrees
C.
Note: You can download parameters for other standard thermocouple types from the NIST database [1]. For information on how to do this, see the Simulink^{®} Approximating Nonlinear Relationships: Type S Thermocouple example. 
The temperature the block subtracts from the temperature at
the thermal port in calculating the voltage across the device. The
default value is 0
°C.
The time it takes the thermocouple temperature to reach 63%
of the final temperature change when a step change in ambient temperature
occurs. The default value is 1
s.
The thermal power required to raise the thermocouple temperature
by one K. The default value is 0.001
W/K.
The temperature of the thermocouple at the start of the simulation.
The default value is 25
°C.
The block has the following ports:
A
Thermocouple thermal port
+
Positive electrical port

Negative electrical port
[1] NIST ITS90 Thermocouple Database http://srdata.nist.gov/its90/main