Experimental evaluation of a small-capacity, waste-heat driven ammonia-water absorption chiller

It is effective to recover waste heat to reduce primary energy consumption. From this point of view, we proposed and examined a new idea of heat transportation using ammonia–water as the working fluid in the system named the Solution Transportation Absorption chiller (STA). As waste heat sources are not necessarily located close to areas of heat demand, conventionally, absorption chillers are located on heat source side and produce chilled water that is transported to heat demand side through pipelines with an insulation. In contrast, the proposed system STA divides an absorption chiller into two parts. The generator and the condenser are located on heat source side while the evaporator and the absorber are on heat demand side. Both the conventional system and STA system satisfy the same boundary condition of heat recovery and heat supply to the demand side, STA can work for transferring thermal energy as the conventional system does even though the temperature of the media is ambient without an insulation. Our previous studies of the STA were based on the experimental investigation with the STA facility where the cooling power was 90[Formula: see text]kW (25.6 refrigeration ton) at the generator temperature 120[Formula: see text]C from 0[Formula: see text]m (normal absorption chiller) to 1000[Formula: see text]m. Thus, the Coefficient of Performance (COP) of STA was found to have almost the same value of 0.65 with conventional absorption chillers without depending on the transportation distances. The objective of this study is to examine the effect of generator temperature from 100[Formula: see text]C to 120[Formula: see text]C on the performance of solution transportation of ammonia–water solution, because the generator temperature is directly linked to the waste heat temperature, so its effect needs to be investigated. The experimental facility tested the performance with 0[Formula: see text]m (normal absorption chiller), 200[Formula: see text]m and 500[Formula: see text]m distance. The results indicate that the effect of the generator temperature and solution transportation distances showed no significant on the COP.

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Compact Diesel Engine Waste-Heat Driven Ammonia-Water Absorption Heat Pump Modeling and Performance Maximization Strategies

Journal of Energy Resources Technology ◽

10.1115/1.4051804 ◽

2021 ◽

pp. 1-28

Author(s):

Christopher M. Keinath ◽

Jared Delahanty ◽

Srinivas Garimella ◽

Michael A. Garrabrant

Keyword(s):

Heat Exchanger ◽

Water Absorption ◽

Heat Pump ◽

Waste Heat ◽

Cooling Capacity ◽

Operating Conditions ◽

Heat Transfer Fluid ◽

Ammonia Water ◽

Absorption Heat Pump ◽

Wide Range

Abstract An investigation of the best ways to achieve optimal performance from a waste-heat-driven ammonia-water absorption heat pump over a wide range of operating conditions is presented. Waste-heat is recovered using an exhaust gas heat exchanger and delivered to the desorber by a heat transfer fluid loop. The absorber and condenser are hydronically coupled in parallel to an ambient heat exchanger for heat rejection. The evaporator provides chilled water for space-conditioning with a baseline cooling capacity of 2 kW. A detailed thermodynamics model is developed to simulate performance and develop strategies to achieve the best performance in both cooling and heating modes over a range of operating conditions. These parametric studies show that improved coefficients of performance can be achieved by adjusting the coupling fluid temperatures in the evaporator and the condenser/absorber as the ambient temperature varies. With the varying return temperatures, the system is able to provide the 2 kW design cooling capacity for a wide range of ambient temperatures.

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