The energy-saving effect of organic fertilizer dryers can be evaluated from the following key indicators and methods:

1. Thermal efficiency: Thermal efficiency is an important indicator for measuring the energy-saving effect of a dryer, representing the proportion of heat effectively utilized by the dryer within a unit of time to the total heat. Generally speaking, the higher the thermal efficiency, the better the energy-saving effect.

2. Waste heat recovery: Evaluate whether the dryer is equipped with a waste heat recovery system. The waste heat recovery system can utilize the heat of exhaust gas to preheat fresh air, thereby reducing energy consumption.

3. Equipment insulation performance: Good insulation performance can reduce heat loss. For instance, the outer cylinder of the dryer can be equipped with an insulation layer, such as glass wool or mineral wool, to reduce heat loss. Equipment with good heat preservation performance has a lower outer wall temperature and less heat loss.

4. Automation and Intelligent Control: Evaluate whether the dryer is equipped with an automated control system, such as intelligent temperature control and self-diagnosis of faults. These functions can enhance the operational efficiency of organic fertilizer equipment and reduce energy waste.

5. Exhaust gas treatment: Evaluate whether the dryer is equipped with an efficient exhaust gas treatment system, such as dust removal and deodorization devices. This can not only reduce environmental pollution, but also recover some heat.

6. Actual operation test: Evaluate the energy-saving effect of the dryer through actual operation tests. For instance, a 24-hour continuous operation test can be conducted to detect the stability of moisture content and energy consumption.

Through the above indicators and methods, the energy-saving effect of the organic fertilizer dryer can be comprehensively evaluated, and more efficient and energy-saving equipment can be selected.