Thermodynamic design data for absorption heat pump systems operating on ammonia-sodium thiocyanate—II. Heating

The free choice of operating temperatures in absorption systems is limited by the Gibbs phase rule and the thermodynamic properties of the working pair. Tables of possible combinations of operating temperatures and concentrations, including flow ratios, Carnot coefficients of performance and enthalpy based coefficients of performance have been presented for ammonia-sodium thiocyanate absorption systems for heating. The interaction of operating temperatures has been illustrated graphically.     

Thermodynamic design data for absorption heat pump systems operating on ammonia-water—Part I. Cooling

The free choice of operating temperature in absorption systems is limited by the Gibbs phase rule and the thermodynamic properties of the working pair. Tables of possible combinations of operating temperatures and concentrations, including flow ratios, Carnot coefficients of performance and enthalpy based coefficients of performance have been presented for ammonia—water absorption systems for cooling. The interaction of operating temperatures have been illustrated graphically.     

Thermodynamic design data for absorption heat pump systems operating on ammonia-sodium thiocyanate—III. Simultaneous cooling and heating

The free choice of operating temperatures in absorption systems is limited by the Gibbs phase rule and the thermodynamics propertie of the working pair. Tables of possible combinations of operating temperatures and concentrations, including flow ratios, Carnot coefficients of performance and enthalpy based coefficients of performance have been presented for ammonia-sodium thiocyanate absorption systems for simultaneous cooling and heating. The interaction of operating temperatures has been illustrated graphically.     

Thermodynamic design data for absorption heat pump systems operating on water-lithium iodide—part I. Cooling

The operating temperatures in the absorption heat pump system fix the absorber and the generator concentration for a given working pair. Derived thermodynamic design data, including Carnot coefficients of performance and enthalpy-based coefficients of performance, with and without an economizer heat exchanger for possible combinations of operating temperatures, are presented for water-lithium iodide absorption systems for cooling. The effects of operating temperatures as well as economizer heat exchanger on the performance of an absorption cooler are illustrated graphically.     

Thermodynamic design data for absorption heat pump systems operating on water-lithium chloride—Part one. Cooling

The free choice of operating temperatures in absorption systems is limited by the Gibbs phase rule and the thermodynamic properties of the working pair. For a given combination of temperatures, the concentrations in the absorber and the generator are fixed automatically. This determines the flow ratio. Therefore for any particular working pair, the coefficient of performance is related to the flow ratio.Tables of possible combinations of operating temperatures and concentrations, including flow ratios, Carnot coefficients of performance and enthalphy based coefficients of performance have been presented for a water-lithium chloride absorption system for cooling. The interaction of operating temperatures has been illustrated graphically. The data obtained are also compared with published data for the water-lithium bromide absorption system under identical conditions.     

Thermodynamic design data for absorption heat pump systems operating on ammonia-lithium nitrate—Part two. Heating

The free choice of operating temperatures in absorption systems is limited by the Gibbs phase rule and the thermodynamic properties of the working pair. Tables of possible combinations of operating temperatures and concentrations, including flow ratios, Carnot coefficients of performance and enthalpy-based coefficients of performance have been presented for ammonia-lithium nitrate absorption systems for heating. The interactions of operating temperatures have been illustrated graphically.     

Thermodynamic design data for absorption heat pump systems operating on water-lithium iodide—part II. Heating

Derived thermodynamic design data, including Carnot coefficients of performance and enthalpy-based coefficients of performance (for heating) with and without an economizer heat exchanger for possible combinations of operating temperatures are calculated for a system in which water is used as a working fluid and aqueous lithium iodide solution as absorbent. The effects of operating temperatures as well as economizer heat exchanger on the performance of an absorption heat pump are illustrated graphically.     

Thermodynamic design data for absorption heat pump systems operating on water-lithium chloride—Part II. Heating

Derived thermodynamic design data including Carnot coefficients of performance, enthalpy based coefficients of performance and flow ratios for possible combinations of operating temperatures for absorption heat pump systems operating on water-lithium chloride for heating are presented. The variations of the derived data with operating temperatures are illustrated graphically. The data obtained for the water-LiCl pair are compared with published data for the water-LiBr pair for identical conditions of temperatures.     

Thermodynamic design data for absorption heat pump systems operating on ammonia—water—Part II. Heating

The free choice of operating temperatures in absorption systems is limited by the Gibbs phase rule and the thermodynamic properties of the working pair. Tables of possible combinations of operating temperatures and concentrations, including flow ratios, Carnot coefficients of performance and enthalpy based coefficients of performance have been presented for ammonia—water absorption systems for heating. The interaction of operating temperatures has been illustrated graphically.     

Thermodynamic design data for absorption heat pump systems operating on ammonia-lithium nitrate—part three. Simultaneous cooling and heating

The free choice of operating temperatures in absorption systems is limited by the Gibbs phase rule and the thermodynamic properties of the working pair. Tables of possible combinations of operating temperatures and concentrations, including flow ratios, Carnot coefficients of performance and enthalpy-based coefficients of performance have been presented for ammonia-lithium nitrate absorption systems for simultaneous cooling and heating. The interactions of operating temperatures have been illustrated graphically.     

Thermodynamic design data for absorption heat transformers—part four. operating on ammonia-lithium nitrate

The Gibbs phase rule and the thermodynamic properties of the working pair limit the choice of operating temperatures. For any combination of temperatures, the concentrations in the absorber and the generator and hence the flow ratios are fixed. For any particular working pair, the coefficient of performance is related to the flow ratio.Tables of possble combinations of operating temperatures and concentrations, including flow ratios, Carnot coefficients of performance and enthalpy based coefficients of performance have beenpresented f for absorption heat transformers operating on ammonia-lithium nitrate. The interaction of operating temperatures has been illustrated graphically.     

Thermodynamic design data for double effect absorption heat pump systems using water-lithium chloride—cooling

In this paper, thermodynamic design data are investigated for the water-lithium chloride pair and a comparative study of the water-LiCl pair with the water-LiBr pair is given, for double-effect absorption cooling systems used for the computer simulation. The computer simulation is based on mass, material and heat balance equations for each part of the system. Coefficients of performance and flow ratios for effects of different operating temperatures are investigated. It is found that the cooling COP is higher for the water-LiCl pair than for the water-LiBr pair, and FR is lower for the water-LiCl pair than for the water-LiBr pair.     

Thermodynamic design data for absorption heat transformers—part III. Operating on water-lithium iodide

Derived thermodynamic design data, including Carnot coefficients of performance, enthalpy-based coefficients of performance with and without an economizer heat exchanger and flow ratios for possible combinations of operating temperatures, are calculated for absorption heat transformers operating on a system in which water is used as the working fluid and aqueous lithium iodide solution as absorbent. The effects of operating temperatures as well as economizer heat exchanger on the performance of the absorption heat transformer are illustrated graphically.     

Thermodynamic study of advanced absorption heat transformers—II. Double absorption configurations

A thermodynamic analysis has been carried out to study the performance of double absorption heat transformers (DAHT) assuming water/lithium bromide as the working fluid. The performance of single (SSHT) and two stage heat transformers (TSHT) analyzed in Part I, was compared with the performance of double absorption heat transformers (DAHT) under the same operating conditions. The results showed that single stage heat transformers (SSHT) were the simplest and most efficient. Greater absorber temperatures were reached with two stage heat transformers (TSHT). However, these systems were in general less efficient than the others and technically the most complex. Double absorption heat transformers (DAHT) were technically simpler than two stage heat transformers (TSHT) and may reach absorber temperature as high as these systems.     

Thermodynamic study of advanced absorption heat transformers—I. Single and two stage configurations with heat exchangers

A thermodynamic analysis was carried out to study the effect of heat exchanger effectiveness (EF) on the performance of single stage heat transformers (SSHT). Moreover, an analysis of three different arrangements of two stage heat transformers was performed using a mathematical model assuming water/lithium bromide as the working fluid. An increase in the solution heat exchanger effectiveness (EF) greatly improved the performance of absorption heat transformers when the absorber temperature was at least 40°C higher than the temperature of the heat supplied to the system. In two stage heat transformers (TSHT), higher absorber temperatures were obtained by coupling the absorber of the first stage to the evaporator of the second. However, higher performance coefficients were obtained in general by coupling the absorber of the first stage to the generator of the second.     

On the performance of advanced absorption heat transformers—I. The two stage configuration

High performance absorption heat transformers based on improved configurations can be proposed with the aim of widening the range of operation of the single stage heat transformer (SSHT). In this paper a two stage heat transformer arranged by coupling the absorber of the first stage to the evaporator of the second stage (TSHT) is analyzed by means of a lumped-parameter mathematical model, written with reference to the water-sulphuric acid system.The computed values of four different indexes of performance show that the proposed TSHT allows one to noticeably increase the gross temperature lift obtainable with a SSHT, while saving a large fraction of the input energy.     

Thermodynamic cycle,correlations and nomograph for NH3NaSCN absorption refrigeration systems

The detailed thermodynamic cycle of the NH₃NaSCN absorption refrigeration unit is presented, based on the thermodynamic properties of the working media. Correlations are developed, which express the coefficient of performance and the cooling capacity in terms of the required evaporation temperature, T_ev, and the available ambient temperature, T_amb. A nomograph is also presented, which shows in a compact form the behaviour of the NH₃NaSCN system and allows direct estimation of its main characteristics. It is concluded that if (T_amb − T_ev) varies from 0 to 40°C, the theoretical coefficient of performance decreases linearly from 95 to 77%. For the same range of (T_amb − T_ev) the theoretical cooling capacity varies from 1150 to 1300 kJ/kg NH₃ if T_ev varies from 0 to −15°C. Under the conditions examined, for T_amb − T_ev > 23°C, the coefficient of performance of the NH₃NaSCN system becomes higher than that of the NH₃LiNO₃ system. The observed increase reached 4% at T_amb − T_ev = 40°C.     

Developments in geothermal energy in Mexico—part sixteen. The potential for heat pump technology

Mexico possesses large amounts of geothermal brine at temperature which are too low to enable electricity to be generated efficiently and economically. Any system which extracts useful energy from a geothermal source is limited by the effectiveness of the heat transfer between the geothermal fluid, which has a tendency to scale, and the relevant components of the system. A heat pump can be used to maintain a temperature difference between two vessels containing pure water and geothermal brine, which is sufficient to enable pure water vapour to flow continuously from the geothermal brine vessel to the pure water vessel. The hot water produced can then be used to operate an absorption cooling system which can be used to store food. Alternatively a heat pump can be employed to increase the temperature of the hot water to produce low pressure stream.     

Periodic high-temperature heat pumps for industrial heat recovery—Part II. Example of application and design of apparatus

Using a drying process as an example, the use of a periodic high-temperature heat pump for industrial heat recovery is investigated. The investigation shows that by using a special control system and two buffer reservoirs, the thermal powers of adsorber, evaporator and condenser can be kept constant in time. The unit under investigation achieves a calculated power density of 6.8 kW/m³ at an effective capacity of 150 kW. A working cycle lasts 3.5 h and the heat ratio is 1.54. The technical design of an experimental unit in tower configuration is described in detail.