Thermodynamic Analysis of a Solar Driven Tri-generation System for Building Applications

Abstract

Energy and exergy analyses and sustainability assessment of a conceptual solar driven tri-generation system with thermal energy storage option for power, water heating and air cooling are performed. The present tri-generation system includes parabolic trough solar collectors (PTC), an organic Rankine cycle for power generation (ORC), an absorption chiller for cooling (AC) and a thermal energy storage system (TES). The effects of solar collector dimension variations, system parameters, environmental conditions and system integration on system energy and exergy efficiencies are parametrically studied. The largest irreversibility occurs in solar collectors due to very high exergy input to solar panels and less conversion of exergy to working fluid. Energy and exergy efficiencies of the present system become 77.1 % and 27 % during day time and 37.6 % and 18.7 % during night time, respectively. The proposed system performs better performance at lower ambient temperature and higher solar radiation and PTC concentration ratio.

Nomenclature

$\overset{.}{\mathrm{Ex}}$ :

Exergy rate, kJ/s

$\dot{\mathrm{I}}$ :

Irreversibility rate, kJ/s

$\dot{\mathrm{Q}}$ :

Heat transfer rate, kJ/s

$\dot{\mathrm{W}}$ :

Work rate, kJ/s

$\dot{\mathrm{m}}$ :

Mass flow rate, kg/s

A_a :

Absorber area, m²

A_r :

Reflector area, m²

C:

Concentration ratio

ex:

Specific exergy, kJ/kg

F_r :

Collector heat removal factor

SI:

Sustainability index

St:

Global solar radiation, kW/m²

α:

Absoptivity

ε:

Emissivity

η:

Efficiency

ρ:

Reflectivity

σ:

Boltzmann’s constant, 5.67 × 10⁻⁸, W/m²K⁴

ω:

Collector width, m

ch:

Chemical

col:

Collector

des:

Destruction

i:

Inlet

o:

Outlet

ph:

Physical

AC:

Absorption chiller

ORC:

Organic rankine cycle

PTC:

Parabolic trough collectors

TES:

Thermal energy storage