An analytical investigation was attempted of a solar driven free-piston Stirling engine driving a second free-piston Stirling engine as a heat pump. A dynamic model and a thermodynamic model with free convection heat transfer were derived. The governing equations were programmed to obtain numerical solutions by computer. Graphs of piston displacements, volumes, pressures, mass cycles, and temperatures versus time are presented. Engine work output, operating frequencies, and efficiencies are calculated. Effects of parameter variations are presented. However, because proper phase angles could not be obtained for this model, the cooling performance of the system could not be evaluated. Limitations of the computer analysis are discussed and areas for possible further investigation are suggested

The residential heat pump is becoming more and more important as a means of heating and cooling homes. The American family is booming increasingly aware of year—round air conditioning in all its various aspects, not only for hosting and cooling the homo, but also for humidity control and air filtration. All those tasks may be accomplished with the installation of a single heat pump unit. Aside from the relatively new concept of cooling buildings during the summer, the heat pump has very distinct advantages when its use as a means of heating alone is considered. The heat pump uses electricity to heat. The individual can perceive immediate advantages in this aspect. The dirt and noxious gases of petroleum or coal combustion are eliminated. The fuel handling and combustion by-product removal equipment are no longer necessary. There is a significant reduction of fire hazard which should be reflected in lower fire insurance costs. The installation of a heat pump would be a distinct advantage architecturally because the heating unit no longer must be placed in a basement or large utility room adjacent to a chimney and fuel storage. In communities where smoke or smog conditions have become serious, extensive installation of electric heating apparatus would be most beneficial. Unless the consumer is willing to assign a monetary value to the afore-listed advantages of the heat pump, he will generally find that in areas where electricity costs over 1-1/2 cents per KWH, it is more expensive to operate than a conventional heating plant.(1O) This figure will of course vary with local fuel costs, heat loads, and heat pump coefficient of performance (COP). In recent years power companies have enthusiastically encouraged the widespread installation of electric heating apparatus, such as the heat pump, by attempting to make their operating costs competitive to other forms of heating. The reason for this encouragement may easily be detected by studying power consumption statistics. The influx of an increasing number of electrical appliances into the home has greatly increased the average power consumption in most areas. However this power consumption varies greatly with the time of day, being at a peak in the early evening, and at a relatively very low minimum in the early morning hours. The utility companies must install sufficient capacity to carry these peak loads, and therefore have machinery idle or operating below rated load and efficiency during the minimum consumption periods. To help offset this economically adverse condition, the power companies are in many areas willing to give rate discounts to consumers using electric heating, as the greatest capacity demands are placed on these units during the minimum power consumption hours. Owners of heat pumps may receive power rate discounts generally in one of two ways, either by a reduced cost per KWH over a certain number, or by the installation of a power meter in which time is integrated with the rate of flow of power, giving a separate or a numerically reduced reading during the off peak hours. The former method is in more widespread use today, however the latter method, although more involved and costly, seems to be more in line with power company objectives. The author has been commissioned as consultant to the architect to design a heat pump system for a proposed residence for Brig. General C. H. Shuey, U.S.H.C. (Ret.). This home is to be built on Sinnepuxant Bay, Maryland. The architect has specified heating is to be accomplished by means of a radiant floor panel. This requirement together with the proximity of a boundless supply of water to use as the heat pump sink and heat source, suggests the use of a water-to—water heat pump system. As a radiant floor panel cannot be used to cool, auxiliary air refrigerating apparatus will have to be installed. The objects of this thesis will be to compute the heating and cooling requirements for the building; to design the radiant floor panels and auxiliary cooling apparatus; and to design the water-to-water heat pump and its associated equipment. / Master of Science

All available information on heat pumps was read and the articles pertaining directly to design, operation, and the overall performance of air-to-air heat pumps were included in the Review of Literature. The advantages and disadvantages of the basic types of systems and their heat sources were explained. A few of the outstanding units as well as small commercial units were discussed, but the data published on these units were very limited as to design and operating values. One of the major problems encountered with air-to-air heat pumps is the defrosting of the outside coil. Several methods were outlined but the best solution for defrosting the coil would depend upon the conditions pertaining to each unit. Several suggestions were outlined where research is needed for the proper utilization of air as a heat source and sink. arter several trial and error solutions the system was designed to give a conditioned air temperature of 100 degrees F for an outside temperature of 30 degrees F and a heat de= Livery of 436.3 Btu/min. The assumed room temperature was 75 degrees F which gave a 25 degree differential across the inside coil, With an 18 degree differential across the outside coil a refrigerating effect of 338.0 Btu/min could be picked up from the outside air. These values appeared to give the best operating conditions, The tubing was sized accordingly and considerations were given to the fact that the vapor lines would be used for both cycles. The stands were constructed and the component parts of the system were mounted on their respected stands. The piping, duct, and electrical work were completed. ‘The design and construction of each of these phases was done with emphasis on clarity, simplicity, and ease in operation and maintenance. The valves numbered 1 through 12 are the control valves. The system is operated on the heating cycle with the even-numbered valves opened and the odd-numbered valves closed. All the control valves, except the expansion valves and their bypasses, are located on the control board. A dehydrator and oil separator were installed in the pining circuits. A two-wattmeter method of power measurement was installed on the unit. This method enables the operators to determine the power supplied to each motor and instantaneous power when the load on the unit is changing. Each of the motors is protected by fusible disconnect boxes. The procedure for starting, operating, and shut down was explained with emphasis on the factors that should be watched for safe and satisfactory operation. The calculations were based upon the conditions of the air, the heat picked up from the outside air, the work supplied to the motors, and the heat gained by the room air. / Master of Science

Typescript (photocopy). / Digitized by Kansas Correctional Industries

D. Tech. Engineering: Mechanical. / Discusses the main objective of the study is to carry out a theoretical and experimental study of a water-to-water CO2 heat pump system and improve its performance by optimizing its working parameters and conditions. The optimization process will be based on South African conditions.Specific objectives to meet the required goal are: 1. Carry out the installation and experimental analysis of a water to water CO2 heat pump system.2. Evaluate the reliability of the system using statistical means through regression analysis and create relationship models between the input and output parameters of the system.3. Execute a thermodynamic analysis of the selected system and evaluate the most important factors that affect its energy efficiency, then identify and evaluate possible system improvements and optimum operating conditions. 4. Compare available heat pump related kinematic and mathematical models and evaluate the best model to describe the operations in the system under local operating conditions. Suggest further improvements to the models and evaluate these too.5. Perform computer modelling and simulations to analyse the CO2 heat pump system,supplement the measurements from the test rig and compare the results.

No description available.

Call number: LD2668 .T4 1983 J66 / Master of Science

Deep gold mines use a vast amount of water for various purposes. After use, the water is pumped back to the surface. This process is energy intensive. The control is traditionally done with manual interventions. The purpose of this study is to investigate the effects of automated control on mine dewatering pumps. Automating mine dewatering pumps may hold a great number of benefits for the client. The benefits include electricity cost savings through load shifting, as well as preventative maintenance and pump protection procedures. By automating pumps, the client will benefit from operating more cost effectively and realising electricity cost savings. The equipment needed for pump automation and the procedures involved in the process are discussed as part of this study. A DSM project was implemented in the form of a pump automation project. All safety and quality procedures were followed and training was provided where needed to ensure that personnel understand their duties and responsibilities. This ensures the sustainability of the project after completion. The performance of the project was tested in manual mode, manual scheduled control, manual scheduled surface control and auto control. Manual intervention achieved the highest electricity cost saving of R8.25 million (11.4 MW load shift saving). To achieve this saving the system was exhausted to a point where columns and infrastructure started failing. Auto intervention achieved an electricity cost saving of R5.57 million (7.7 MW load shift savings). The auto intervention achieved a lower electricity cost savings compared to the manual intervention. However, taking all factors into account, such as the damage to infrastructure after a period of manual control, the auto intervention proved the best balance for controlling mine dewatering pumps to achieve savings on the cost of electricity and system sustainability for optimal control. Automated systems can avoid system overload and protect the infrastructure from exhaustion. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

Deep gold mines use a vast amount of water for various purposes. After use, the water is pumped back to the surface. This process is energy intensive. The control is traditionally done with manual interventions. The purpose of this study is to investigate the effects of automated control on mine dewatering pumps. Automating mine dewatering pumps may hold a great number of benefits for the client. The benefits include electricity cost savings through load shifting, as well as preventative maintenance and pump protection procedures. By automating pumps, the client will benefit from operating more cost effectively and realising electricity cost savings. The equipment needed for pump automation and the procedures involved in the process are discussed as part of this study. A DSM project was implemented in the form of a pump automation project. All safety and quality procedures were followed and training was provided where needed to ensure that personnel understand their duties and responsibilities. This ensures the sustainability of the project after completion. The performance of the project was tested in manual mode, manual scheduled control, manual scheduled surface control and auto control. Manual intervention achieved the highest electricity cost saving of R8.25 million (11.4 MW load shift saving). To achieve this saving the system was exhausted to a point where columns and infrastructure started failing. Auto intervention achieved an electricity cost saving of R5.57 million (7.7 MW load shift savings). The auto intervention achieved a lower electricity cost savings compared to the manual intervention. However, taking all factors into account, such as the damage to infrastructure after a period of manual control, the auto intervention proved the best balance for controlling mine dewatering pumps to achieve savings on the cost of electricity and system sustainability for optimal control. Automated systems can avoid system overload and protect the infrastructure from exhaustion. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

Valve wear has been a serious problem to engine designers and manufacturers for many years. Although new valve materials and production techniques are constantly being developed, these advances have been outpaced by demands for increased engine performance. The drive for reduced oil consumption and exhaust emissions, the phasing out of leaded petrol, reductions in the sulphur content of diesel fuel and the introduction of alternative fuels such as gas all have implications for valve and seat insert wear. The aim of the project has been, through the use of a representative bench test and engine testing, to diagnose the predominant wear mechanisms in diesel engine inlet valves and seats. This information was then to be used with other test data to develop a model for predicting valve recession and other tools to assist in solving valve failure problems. Test apparatus has been developed that is capable of providing a simulation of the wear of both inlet valves and seats used in automotive diesel engines. Investigations carried out using the apparatus have shown that the valve and seat wear problem involves two distinct mechanisms; impact of the valve on the seat insert on valve closure and sliding of the valve on the seat under the action of the combustion pressure. Wear has been shown to increase with valve closing velocity, combustion load and misalignment of the valve relative to the seat. Lubrication of the valve/seat interface leads to a significant reduction in valve recession. Valve rotation ensures even wear and promotes debris removal from the valve/seat interface. During testing it was established that resistance to impact was the key seat material property determining the amount of recession that occurred. A semi-empirical wear model for predicting valve recession has been developed based on the fundamental mechanisms of wear determined during test work. Model predictions were compared with engine tests and tests run on the bench test-rig. The model can be used to give a quantitative prediction of the valve recession to be expected with a particular material pair or a qualitative assessment of how parameters need to be altered in order to reduce recession. Flow charts have also been developed, based on the review of literature, failure analysis and modelling carried out, to assist in diagnosing and rectifying valve/seat failures and to help in reducing valve recession by design. The test apparatus, valve recession model and design tools can be integrated into an industrial environment in order to help reduce costs and timescales involved in solving valve/seat wear problems using the current trial and error methods.