chapter 5: concentrating solar colelctors and concentrating solar power

the area that receives the solar radiation is increased by what?

concentrators

collector

receiver and concentrator

receiver

absorbs q, the heat flux, but it is not uniform

concentrator

directs radiation to the receiver

aperture

area through which the solar radiation enters into the concentrator

concentrated solar power:

• high/low____ incident radiation fluxes ~_____

• high/low____ temperatures of the fluid ~____ C

• only use _____ radiation

• does it have heat storage? why?

• high, 1 MW/m2

• high, 1000

• beam

• yes to increase the capacity factor

what is a?

tubular absorbers with a diffuse back reflector

what is b?

tubular absorbers with specular cups reflectors

what is c?

plane receiver wit plain reflectors (V-trough)

what is d?

multi sectional planar concentrator

what is e?

compound parabolic concentrator

what is f?

parabolic trough

what is g?

fresnel concentrator

what is h?

heliostats with a central receiver

Compound parabolic collector

• concentrator: ?

• ?

• ?

• ?

• ?

• ideal

• non-imaging

• truncated

• no tracking

linear fresnel

• Power:

• Tracking system:

• Focus

• Installed ratio:

• 10-50 MW

• 1 axis

• lineal

• >3%

parabolic trough

Power:

Tracking system:

Focus

Installed ratio:

• 30-80 MW

• 1 axis

• lines

• >84%

parabolic dishes

Power:

Tracking system:

Focus

Installed ratio:

• 5-25 kW

• 2 axis

• punctual

• <1%

central receiver (heliostats)

Power:

Tracking system:

Focus

Installed ratio:

• 10-200 MW

• 2 axis

• punctual

• >12%

components of a parabolic trough

absorber tube, concentrator, frame

parabolic troughs

Heat transfer fluid:

Thermal energy storage:

Power block:

• water, synthetic oils & silicones, molten salt

• 7.5 hr

• power block

linear fresnel

Heat transfer fluid:

Thermal energy storage:

Power block:

• water, molten salt

• N/A

• organic ranking at low temp and low power

components of a linear fresnel

frame and primary concentrator

central receiver: heliostats

mirrors that surround the tower to focus the solar radiation in the central receiver on the top of the tower

there are more heliostats in the ____ part of the tower because they are more efficient

northern

central receiver components

central receiver, tower, heliostats

central receiver

Heat transfer fluid:

Thermal energy storage:

Power block:

• molten salt, steam water, gas (air and co2)

• 10 hr

• rankine for molten salt and steam water and brayton for gas

dish stirling components

parabolic concentrator, solar tracking system in azimuth and elevation, receiver, stirling engine

dish stirling

Heat transfer fluid:

Thermal energy storage:

Power block: no info

efficiency:

• gas (he, h, air), vaporized liquid metal (Na)

• n/a

• n/a

• 20-40%

subsystems of solar thermal power plants

solar collector, thermodynamics cycle, electric generator

for solar thermal power plants, ___ temperature is required to obtain an acceptable efficiency

high

CSP can generate when?

• during sunny hours

• continuously with thermal storage or fossil backup

thermal storage characteristics :

high or low energy density in the storage medium?

high

thermal storage characteristics:

good or bad thermal transfer between the HTF and storage medium

good

thermal storage characteristics:

what two types of stability in the storage medium?

chemical and mechanical

thermal storage characteristics:

reversible or not for a huge number of charge/discharge cycles?

reversible

thermal storage characteristics:

low or high thermal losses

low

thermal storage characteristics:

is it easy to regulate and control?

yes

solar multiple and capacity factor affect what?

efficiency, thermal storage size, cost

sensible heat solar storage

thermal capacity per unit of mass due to a temperature increment

latent heat solar storage

thermal energy is loaded and unloaded through the phase change, meaning a high energy density at constant temperatures

chemical solar storage

storage trough reversible chemical reactions, huge energy density (10x latent heat)

simple storage medium

HTF is the same as the storage fluid

dual storage medium

HTF and storage medium are different, for a lower cost

parabolic trough power plant

Concentration:

Power:

Cost:

Efficiency:

• 30-80

• 30-80

• 4.5

• 14-20%

linear fresnel power plant

concentration:

power:

cost

efficiency:

• 20

• 10-50 MW

• 3.1

• 18%

central receiver power plant

concentration:

power:

cost:

efficiency:

• 1000

• 20-150 MW

• 6

• 25-30%

dish stirling power plant’s four processes:

1. isothermal compression

2. isochoric heat addition

3. isothermal expansion

4. isochoric heat rejection