3. Design considerations for thermoelectric cooling photovoltaic (TEC-PV) devices

a. Building integration parameters: Thermoelectric cooling (TEC) devices can be fixed in a building on wall and ceiling as radiant cooling panels. Due consideration should be given for placing thermoelectric modules with or without heat sinks. Heat sinks can be placed towards building interior zone and towards exterior zone. The thermoelectric modules can be placed on a cut section of a wall, with provision of cooling the hot side heat sink. The thermoelectric cooling devices can also be fixed on a window or a skylight. Proper protection

has to be ensured from air infiltration and direct solar radiation for TEC devices fixed on windows and skylights. The mode of operation for winter can be reversed by changing the direction of current of thermoelectric modules. TEC devices can also be fixed inside air supply ventilation ducts. Buildings requiring cooling and heating with dual duct ventilation system are good choice for using thermoelectric devices inside ducts.

2.2. Exergy expressions

320 Bringing Thermoelectricity into Reality

The specific exergy of fresh moist air into the duct is expressed as [15]:

"

� � Tf ,in � To � To � ln

1 þ 1:608wf ,in � � � ln

The reference temperature (To) and the humidity ratio (wo) is defined as the indoor air temperature and humidity ratio during hot and humid season. Ra is the thermal resistance of air. cpa is

<sup>þ</sup> <sup>1</sup>:<sup>608</sup> � Ra � To � <sup>w</sup> � ln wf ,in

Thus from Eq. (13), total exergy of the fresh air flow into the duct is expressed as:

The exergy of the heat transferred between the fresh air and TEM is expressed as:

ExQf <sup>¼</sup> <sup>1</sup> � To

Tf ,in To

1 þ 1:608wf ,in � � ð Þ 1 þ 1:608wo

Exf ,in ¼ r � Ma � exf ,in (14)

� Qf (15)

� 100% (16)

(13)

� �

#

wo

/h.

Tc � �

� <sup>100</sup>% <sup>¼</sup> Exf , out � Exf ,in

3. Design considerations for thermoelectric cooling photovoltaic (TEC-PV)

a. Building integration parameters: Thermoelectric cooling (TEC) devices can be fixed in a building on wall and ceiling as radiant cooling panels. Due consideration should be given for placing thermoelectric modules with or without heat sinks. Heat sinks can be placed towards building interior zone and towards exterior zone. The thermoelectric modules can be placed on a cut section of a wall, with provision of cooling the hot side heat sink. The thermoelectric cooling devices can also be fixed on a window or a skylight. Proper protection

� � Exelec

exf ,in ¼ cpa þ wf ,in � cpv

þ Ra � To

specific heat of moist air and cpv is specific heat inside the duct.

where r is density of air and Ma is airflow rate m<sup>3</sup>

where Qf is heat transfer rate (W).

devices

The system exergy efficiency is expressed as:

<sup>η</sup>Ex <sup>¼</sup> Exeff Exsup

where Exeff is effective Exergy, Exsup is electrical exergy supplied.

